525 and 630 denier HT Ballistic Nylon

Our HT Ballistic nylon is a lighter weight version of our 1050 HT Ballistic nylon with a twist. Literally, it’s the same construction of two yarns woven side-by-side in a basket pattern (which is what has come to define a “ballistic” weave), but with the added feature of the individual yarns being twisted as they are laid down. This twisting mitigates the potential effects of abrasion by sending any broken filaments on the surface of the fabric back into the weave, instead of leaving a broken filament lying loose on the surface.

It has a very similar look and surface feel as our 1050 HT Ballistic nylon; its abrasion resistance is right in there with the 1050d, testing at over 10,000 cycles on the Taber machine. It shares the luxuriant sheen of 1050 Ballistic—if anything, it looks even richer. It has just about the same weight (10.5 ounces per square yard / 360 grams per square meter) and body as 1000 denier Cordura@, sans the fuzzy texture. This makes it an ideal all-around fabric for many applications, as it won’t collect pet hair, sweater lint, or snow.

A note about the denier: we are beginning a transition from our 525d ballistic nylon to 630d ballistic nylon. They’re virtually the same fabrics — both high-tenacity yarns and even though 630d is ever so slightly heavier on paper, we can hardly feel it. 30d will offer us a continuously available supply (the base yarns will continue to be stocked by our mill) at an ever-so-slightly increased cost.

We’ve treated this fabric with an extra-heavy urethane coating (1.80 ounces per square yard / 60 grams per square meter) on the inside; the exterior features an environmentally-friendly C6 Durable Water Repellant (DWR).

This fabric is woven and finished in South Korea with Invista Cordura® yarns from Canada.

210 Denier HT Ballistic Nylon

Our 210 denier HT Ballistic nylon certainly pushes the limits of what we tend to think of as “ballistic” nylon. Though it is 1/3 the weight of original 1050 Ballistic (5.8 oz per sq yard / 195 grams per square meter), it’s made with the same construction of two yarns woven side-by-side in a basket pattern. It’s basically the little sibling of our 525 denier HT Ballistic nylon, and features similarly twisted yarns (see the description of 525 denier HT Ballistic nylon for the skinny on why twisting the yarn is important).

Our 210 denier HT Ballistic nylon has a similar matte look and smooth feel as our 1050 HT Ballistic nylons. It is similar in heft to 420 HT Parapack, and weighs about 25% less yet tests higher for abrasion resistance (over 5,000 cycles on our Taber testing machine). It's an excellent fabric choice for linings, dividers and accessories.

Because our 210 denier HT Ballistic nylon is intended as a lining/interior fabric, we’ve given it a relatively light urethane coating on the inside (0.85 ounces per square yard / 30 grams per square meter); the exterior features an environmentally-friendly C6 Durable Water Repellant (DWR).

This fabric is woven and finished in South Korea with Invista Cordura® yarns from Canada.

Our 210d HT ballistic nylon is made for us in a bluesign® certified fabric mill.

1000 Denier Cordura®

1000 denier Cordura® fabric was originally developed as a fiber to incorporate into automobile tires as belting. In the 1970s, Dupont introduced it to the outdoor industry as a fabric for backpacks and other gear. Prior to the introduction of 1000 denier Cordura®, most outdoor backpacks were made of 420 denier HT nylon Classic Parapack. Because it isn't high tenacity like 420 denier HT nylon Classic Parapack or our 1050d US HT ballistic nylon, Cordura® is relatively easy to dye, and is available off-the-shelf in a wide variety of colors.

Denier is a measurement of the size (weight actually) of the yarn from which a particular fabric is woven. It is the weight in grams of 900 meters (that's a little over half a mile!) of the specific yarn. The yarns, in turn, are spun of smaller fibers which can also be measured in denier. We are referring to the size of the yarn, and not the size of the individual fibers.

1000 denier Cordura® has a urethane coating on the backside (used for the inside of our packs) and a Durable Water Repellant treatment applied to the face side (used for the exterior of our bags). The exterior DWR treatment causes water to bead up on the surface and run off, while the urethane coating acts as an impermeable waterproof barrier. DWR is a surface treatment and can wear off over time. It's easy to see if the DWR is still present and working simply by dribbling a few water droplets onto the surface of the fabric: if the water soaks into the fabric without beading up and running off, the DWR has worn off. It can be reapplied by anyone using Nikwax Tent & Gear Spray or a similar product.

1000 denier Cordura® is a texturized fiber: air is blown through the fibers as they are extruded which causes some of the fibers to become discontinuous. This basically makes the surface of the woven fabric "fuzzy", creating an appearance similar to that of cotton canvas. The discontinuous fibers also absorb some of the energy of abrasion by moving (picture tall grass in the wind). The fibers also help to hide damage to the surface of the fabric caused by abrasion: the fibers broken by abrasion are masked by the already "broken" discontinuous surface fibers. Discontinuous fibers collect much more lint, pet hair, fuzz and snow than filament fibers (420d HT nylon Classic Parapack and our 1050d US HT ballistic nylon are both filament fiber fabrics). Because of its texture, 1000 denier Cordura® frays less at its cut edge. With modern coatings on the backsides of the fabrics, this is typically not a problem; buy a vintage 1000 denier Cordura® pack off eBay and you might see how this used to be an issue. Because we finish 100% of any exposed internal seams on all of our bags, this has never been an issue or consideration for us.

In 2004, Dupont sold its fiber division to Invista. Since then, Cordura® has evolved to be a brand name and umbrella for a wide variety of fabrics, some with discontinuous fibers and some not. 

500 Denier Cordura®

500 denier Cordura® is slightly lighter weight version of 1000 denier Cordura®. It has good abrasion resistance, more-than-adequate tear strength, and excellent dyeability; 500 denier Cordura® can thus be a very good, all-around bag fabric.

Note that while the denier (weight) of the fibers in 500 denier Cordura® is one-half (50%) of the 1000 denier fabric, it's a more densely woven fabric: because the fibers are smaller in diameter, they can be packed more closely together. So while the fibers are half the weight, there are more of them, making 500 denier Cordura® fabric roughly 2/3 the weight of 1000 denier Cordura® fabric.

For several decades, 500 denier Cordura® was our first choice as an interior fabric, as well as for accessories and even for some exterior applications. However, it shares 1000 denier Cordura®'s affinity for lint and pet hair, so we've been replacing it with filament fabrics like Halcyon 200d and 420d HT Parapack.

X-Pac® RX-30

X-Pac® RX30 is our first PFC-Free, 0-Chain DWR Fabric, and it's really cool! In addition to being PFC-Free, it's also made with 100% post-consumer filament, specifically from recycled PET bottles collected from the east coast of the United States.

X-Pac® is different a different beast than most of our materials, instead of being a single woven fabric, it's a laminate fabric. What this means is that it has layers of material (3 layers of polyester in this case) bonded together with an adhesive to create a composite material with a layered structure with different properties in each layer to provide specific benefits like water resistance, structure, strength, and texture. In the RX30, the backing fabric is a thin film of polyester, the middle layer is Dimension Polyant's X-Ply® material made with post-consumer recycled polyester, and the face is a 300 denier 100% recycled polyester. It's finished off with a PFC Free DWR.

This fabric is made in the United States.

630 Denier 50% Recycled Nylon

Our 630 denier nylon fabric is woven of 50% pre-consumer recycled nylon; both the recycled and non-recycled fiber is sourced in South Korea, and the fabric itself is woven, dyed and treated there in a bluesign mill.

When the opportunity presented itself to utilize a 50% pre-consumer recycled nylon, we jumped on it: we received swatches, Taber (abrasion) tested them, performed various other tests, made sample bags, and were quite pleased with the results.

Previously, the only recycled fabrics out there have been recycled polyester. It’s not like we have something against polyester (PET) per se: it’s a very useful plastic for many applications, and its recyclability is great -- endlessly turning pop bottles into fleece pullovers and back again is pretty cool. However, polyester’s performance as a bag/backpack fabric is notably subpar when compared to nylon: its abrasion resistance and tear strength are lacking, and a bag made from polyester will tend to experience wear issues before a similarly constructed nylon bag.

A backpack’s or bag’s environmental footprint is far more than simply that of its primary fabric: lots goes into the making and shipping of its zippers, buckles, webbing, thread etc, and furthermore into the cutting, sewing and shipping of the finished item. We've concluded that it’s better to make one long-lasting bag than two (or more) bags with a shorter lifespan. We’re excited to offer a more environmentally friendly fabric, without sacrificing the long-term durability of nylon.

Our 630d fabric is a filament fabric, so it’s smooth like our 210d, 525d and 1050d ballistic, and doesn’t tend to collect pet hair or fussels. Unlike those fabrics, it’s a plain weave (a 1X1 construction as opposed to the ballistic, 2X2 or “basket weave”) and so its texture has a slightly more coarse appearance, reminiscent of 1000d Cordura. Its hand (or stiffness) is somewhere between 420 Parapack and the 525 2x2; at 7.8 oz per square yard / 265 grams per square meter, it’s just a bit heavier than 420 Parapack.

420 Denier HT nylon Classic Parapack

420 denier, high tenacity, type 6,6 nylon fabric (Parapack) was originally developed for the military for use in parachute backpacks—the thing on the guy’s back that holds the parachute. Paratroopers needed a fabric that was smooth and wouldn't hang up on anything as they jumped from the plane; it had to be light (obviously); and it needed to be strong so as not to be easily punctured or abraded.

You can think of 420 denier Parapack fabric as the little brother of 1050 denier Ballistic. Like 1050 Ballistic, 420 Parapack fabric is densely woven of high tenacity, filament nylon yarns. Both are also type 6,6 nylon, as opposed to the more common type 6. Type 6,6 has greater tensile strength than type 6, and very importantly type 6,6's melting temperature is higher by 40°C (70°F). This is a very good thing because the degradation of a fabric caused by abrasion is largely the result of heat building up during abrasion and damaging the material. A higher melting point means better abrasion resistance.

Like 1050 HT Ballistic cloth, 420d HT Parapack is relatively hard to dye and can sometimes have a heathery appearance.

Also like 1050d HT Ballistic, it's a filament fabric (as opposed to texturized) and tends not to accumulate snow, lint, or pet hair.

We got reacquainted with 420d Parapack back in 2013 as we developed the retro-inspired Guide's Pack and Founder's Briefcase. It has a great hand, a dense weave, and a less sparkly appearance than its cheaper imported cousins. We love it!

400 Denier Halcyon

Halcyon 400 denier is the big brother of our Halcyon 200 denier, and in a way, a cousin to 420HT Parapack. Made for us in Japan, it's a ripstop fabric woven of 400 denier nylon (base fabric) with a square grid of 420 denier UHMWPE (ultra-high-molecular-weight polyethylene) yarns every .25" / 6mm. UHMWPE is one of the strongest fibers known to man, and is almost impossible to tear.

Halcyon 400d is similar in feel and weight to our 420HT Parapack, though with its grid of UHMWPE, its appearance is somewhat more modern or "technical". And while the base material is not 6,6 nylon, it is still considered to be "high tenacity"; without the UHMWPE grid, the base fabric is what most of the world's automotive airbags are made of.

Because of its remarkable tear strength and very good abrasion resistance, Halcyon 400d is an excellent choice as a lighter-weight alternative to 1050d ballistic nylon for travel bags and backpacks. Note that at the end of the day, the base fabric is only about one-half the thickness of 1050d ballistic nylon, and you'll need to treat your Halcyon 400d bag with a bit of respect: no kicking your bag along the floor at the airport, or tossing it from a moving vehicle. That said, the ripstop grid of UHMWPE makes it very difficult to cut or tear, and will tend to foil most attempts at slash-and-run theft.

Our 400d Halcyon is dyed and woven in a bluesign® certified fabric mill and is finished in an OEKO-TEX® certified facility. OEKO-TEX® is a union of 18 independent research and test institutes in the field of textile ecology in Europe and Japan. The goal of the OEKO-TEX® production facility certification is to ensure environmentally friendly production processes in the long term, to improve health and safety and to promote socially responsible working conditions at production sites.

Our Halcyon 400d is available both with the conventional white (undyed) UHMWPE grid, as well as a black (actually very dark grey) UHMWPE grid. Either way, we think this is a handsome as well as supremely functional fabric.

200 Denier Halcyon

Halcyon 200d is a high-tech, high-performance alternative to the ubiquitous "oxford" cloths commonly used in backpacks and travel bags for interlinings, internal dividers and accessories. Halcyon 200d is a ripstop fabric woven of 200 denier nylon (base fabric) with a square grid of 200 denier UHMWPE (ultra-high-molecular-weight polyethylene) yarns every .25" / 6mm; an additional diamond ripstop pattern adds to its sophisticated aesthetic.

The grid of UHMWPE adds no weight but makes Halcyon 200d virtually impossible to tear. This is particularly important when paired with a heavy-duty exterior fabric like 1050 Ballistic nylon: the seam joining exterior fabric to lining fabric can be a relatively weak point if the two fabrics have disparate tensile strengths.

Our 200d Halcyon is dyed and woven in a bluesign® certified fabric mill and is finished in an OEKO-TEX® certified facility. OEKO-TEX® is a union of 18 independent research and test institutes in the field of textile ecology in Europe and Japan. The goal of the OEKO-TEX® production facility certification is to ensure environmentally friendly production processes in the long term, to improve health and safety and to promote socially responsible working conditions at production sites.

210d nylon with an UHMWPE ripstop grid has become our go-to lining fabric.

210 Denier Cerylon

Cerylon 210 is a 210 denier, 100% high-tenacity nylon fabric – a next of kin to our Halcyon. (Ceyx was Alcyone’s husband, for the record.) Cerylon has a formidable tear strength (though it’s not quite as high as Halcyon) that is more than adequate for its intended use as a fabric for lightweight accessories, internal dividers or as a lining material. It has a “double wall” ripstop pattern, which we’ve added as a nod to its mate Halcyon. We have the mill make Cerylon with twisted yarns just like our heavier weight fabrics — twisted yarns increase the density of a fabric, as well as help to hide cosmetic abrasion.

In developing Cerylon, Tom imagined a fabric which we could offer as another choice along side of Halcyon. Though many customers appreciate the look of the white ripstop grid that is Halcyon’s trademark, we had feedback from other customers who preferred a more subtle aesthetic. Furthermore, Tom wanted us to be able to recycle scrap fabric at some point in the future (when the technology and economics make that an option for us), and knew that a mixed-fiber fabric like Halcyon (nylon and UHMWPE) would be much more difficult to recycle. Though not currently an option for us, we hope to recycle our 100% nylon fabric scraps someday, and Cerylon moves us a step closer to being able to do that.

120 Denier Aether

Aether is an ultra-light, 100% nylon fabric from Japan. It has a unique and complex construction, combining 30 denier monofilament (warp and weft) with both 100 denier and 200 denier yarns in a micro-ripstop weave to further increase its tear strength. Like most of our fabrics, Aether is coated on the backside with urethane for weather resistance, as well as having a surface treatment of durable water repellant.

This is a very light fabric, useful for those trying to save weight wherever possible. Though its hand is a bit crisp or papery when new, we greatly prefer Aether's esthetic over commonly available silicone-coated nylons. It's light, but surprisingly tough.

100 Denier Piscine

Dobby-woven and South Korean-made, this 100 denier fabric is similar in weight to Aether. The geometric pattern that is a signature of the dobby weave (which is literally a weave that repeats small, simple geometric patterns and textures by controlling the logitudinal, or warp, threads of a weave) reminded of fish scales and thus we declared it Piscine!

Piscine is made of high tenacity nylon with a ripstop pattern and is coated, like most of our fabrics, with urethane on one side and C6 durable water repellant on the other for weather resistance.

As with Aether, it's a very light fabric that's great for lining smaller bags while saving on weight. It has a soft, flexible hand and is nice and sturdy.

Buckles/Parts

In the latter part of the 20th century, injection-molded plastic buckles and fasteners replaced most of the components of bags and backpacks that had been previously made of metal. Plastic parts are lighter weight and won't corrode, and are more pleasant to the touch, especially when it's cold.

Many of the plastic parts used on modern bags are one-for-one copies of the old metal parts, one exception being "side release" buckles (often still called Fastex buckles, after the original company that introduced the design). The precision of the injection molding process, and the careful formulation of the plastics themselves, allowed engineers to build these now ubiquitous buckles so that they're flexible enough snap together, and rigid enough to stay snapped. The basic concept of the over-centering, interlocking prongs is now used by buckle makers around the world to offer a myriad of side-release and similar fasteners.

Most of these plastic parts are molded of either nylon or acetal: both materials have advantages and disadvantages. Nylon is a bit softer than acetal—this especially of note when used in the above-mentioned side-release buckles: nylon parts don't snap together with the same crispness that acetal parts do, making the nylon quieter and less likely to pinch your fingers in use. However, unlike acetal, nylon can absorb a small amount of atmospheric moisture and when the temperature drops below 32F/0C, this tiny amount of moisture can freeze and cause the buckle to become brittle and break.

Metal parts can still offer the greatest strength and durability in certain applications; for example, die-cast zinc is used in swivel snap-hooks for shoulder straps, and brass in grommets and snaps. However, whether it's plated or painted, the surface coating on metal parts can scratch and wear over time, revealing the base metal beneath.

We'll use plastic and metal hardware on our bags, whichever provides the best utility and durability for a specific application. For plastic components, both nylon and acetal are utilized: for the side-release buckle closure on a bag's flap, for example, we use an acetal female half and a nylon male half—this combination leverages the best performance from both materials. Our metal snap-hooks are electrostatically plated black twice, just to be sure.

Coatings

Most of our fabrics utilize two treatments to make them as weatherproof as possible:

The exterior surface of the fabric gets a treatment of DWR (“Durable Water Repellant”), which is more or less what ScotchGard® is. This chemical is applied to the face of the fabric, encouraging water to bead up and run off rather than soaking into the yarns and through the weave of the cloth. DWRs are the first line of defense against moisture getting into your bag.

Unfortunately, the chemicals used for DWRs do not bond permanently to the fabric's surface. This means that from time to time, you may need to renew the treatment to maintain your bag or pack's weatherproofness (see below). DWRs' non-permanence is also bad for the planet because after departing from the fabric, these chemicals tend to persist in the environment and are not good for people or other life forms. For decades the chemical of choice was an eight carbon chain PFOA (perfluorooctanoic acid). Like the rest of the industry, we’ve moved to six chain PFOS (perfluorooctane sulfonate), which breaks down much faster into simpler and (theoretically) more benign chemicals. As we move forward, we will remain on the cutting edge of environmentally-friendly DWRs.

As noted above, you may need to renew the surface water repellency of your pack or bag as it ages. We recommend NikWax Tent and Gear Solarproof: we’ve found it’s easy to apply and works well. Nikwax assures us that their product is environmentally safe.

On the backside of most of our fabrics is a coating of urethane, which is more or less waterproof. That said, water that has saturated the weave of the fabric itself will eventually soak through even this coating, which highlights the need for DWR on the front side. While the urethane coating is more durable than the external DWR, over time it can decay from abrasion, oxidation, mildew, and extensive flexing of the base fabric.

In fact, urethane coatings are one of the shortest-lived of all components in our bags—and those of other manufacturers. Because the amount and type of urethane coating can greatly impact the base fabric's tear resistance, a thoughtful choice must be made to balance the competing (or even conflicting) demands on the fabric and the finished bag. A thicker coating can give longer-lasting waterproofing, but can also make the fabric more brittle and subject to tearing; additionally, a thicker coating can have enough inherent tensile strength to make it peel away from the fabric. In our opinion, the coatings we've chosen offer a balance of durability in terms of both waterproofness and fabric strength.

Urethane coating can sometimes become slightly opaque or white over time. We've found this can be a result of the climate in which a bag is used and/or stored (particularly high humidity climates), or to chemical reactions to certain soaps or cosmetics that are either carried in the bag or used to clean it. Generally, this clouding of the urethane coating is purely cosmetic.

As a bag ages, some peeling or degradation of the urethane coating can be expected, especially where the fabric is subjected to excessive flexing (around zipper openings, for example), or excessive internal abrasion (like from the corner of a laptop or tablet). Though this can have a minor effect on a bag's waterproofness, we consider it within the realm of "normal wear and tear.”

There are a few things you can do to prolong the life of your bag's urethane coating. Most important is to make sure to dry out the inside of your bag after it has become wet, whether from something having been spilled inside or from weather soaking through. This is important if you’re storing the bag for any extended period, particularly in high-humidity climates. The urethane can actually get mildewed: you’ll know this is happening because it looks bad (and smells bad, too). To protect the coating from abrasion, you can avoid carrying items that have sharp corners that will poke/wear on the inside of the bag.

The urethane coating on our Halcyon fabrics is not quite as thick as on other fabrics. This is because the UHMWPE yarns cannot survive the heat curing that all-nylon fabrics get when they are coated. Our mill in Japan has developed a proprietary “dry coating” technique that does allow them to apply a coating, but it’s not as thick as standard heat-set urethane coatings. It’s a compromise.

Note that while our fabrics are very weatherproof, they are generally not entirely waterproof. Additionally, our bags are sewn rather than welded or glued together, and are therefore not submersible.

Colors

Modern dyes allow synthetic fabrics to attain (and hold) almost any color we humans can imagine. With such a myriad of choices from which to make outdoor and travel equipment, perhaps restraint is all that we as designers lack. Indeed, some colors and color combinations seem in hindsight to have been such bad ideas that we ought now blush.

When choosing the exterior color for a bag or backpack, it's worth considering whether you need your bag to stand out or blend in. Depending on where and how you travel, this could go either way.

For years, the wisdom in outdoor equipment was to go for bright colors so that you can be found in emergency situations. But when the backcountry started getting more visitors, and the landscape became decorated with red and orange hikers and their gear, colors that blended in became de rigueur. Greens and browns blend well in many outdoor situations, while black and grays might be effective camouflage in urban settings; blues can stand out but still not be visually irritating.

It's good to keep in mind that if other people can't see your bag, maybe you can't either, and you may be more likely to lose it or leave it behind, or be unable to distinguish it from a pile of everyone else's bags. Perhaps choosing a less common color that is yet somewhat subdued can be a compromise. You might be looking at your bag for some time, so if the color makes you smile, all the better.

The interior of a bag is likely to be seen only by you, the user, so you needn't feel so constrained in your color choices. Note that lining a bag with black fabric is a great way to turn it into a prop for a magic show: put clothing and gear into the bag and presto!—they disappear. Light or bright colors allow you to better see the contents of your bag, and a bright interior color can be a fun way to personalize your bag without being too colorful (not that there's anything wrong with that!)

A few backpack and bag fabrics are available to manufacturers "off the shelf" in stock colors. However, if a specific color is desired, you must purchase a "dye lot" of that color, ranging from several hundred to a few thousand yards, depending on the fabric and mill.

At TOM BIHN, we are known for our colors and color combinations (what the industry calls "colorways"). Most of our fabrics are dyed to our specifications and are uniquely ours: our fabric suppliers are regularly "dipping" new swatches based on color samples we submit to them to match. Over the years, we've sent them packets of spices, flower petals, paint chips, and snippets of textiles from other industries. The majority of colors don't make it past this initial stage, but we do like to offer new choices every year. We take more chances with interior colors, though you will see new exterior fabric colors as well. We do not subscribe to any of the fashion or trend services that "predict" (and then end up dictating) next year's colors and styles: as with most other aspects of the TOM BIHN business, we do our own thing, listening to our customers a bit, and mostly following our own sense of aesthetics.

Foams

A large variety of cellular foams are used in making bags and backpacks: some provide cushioning to the user (shoulder straps and handles), some provide protection for items carried (laptops, etc.), and some give a bag body or rigidity.

The density of foam is generally described in pounds per cubic foot (pcf). Density range is anywhere from 1.5 pcf to 20 pcf; lower densities tend to be somewhat soft, and higher densities firmer or more rigid. Foam's properties are further determined by its base material (and various additives), and whether it is open- or closed-cell.

Polyethylene is the base material most commonly used for the foams used by the outdoor and travel goods industries. Linear-linked polyethylene foam is generally used for packaging materials and is not very durable, though sometimes very inexpensive bags will use it. Cross-linking the polyethylene molecules enhances tear and tensile strength and creates a finer cell structure, making cross-linked foams more resilient and durable. Adding a small percentage (8-15%) of EVA (ethylene-vinyl acetate) to cross-linked polyethylene foam gives it a more supple, rubber-like feel; without the EVA, polyethylene foam can be somewhat stiff and boardy, which can be just what is required in certain applications.

With closed-cell foam, the "cells" are discrete bubbles of gas, completely sealed inside the base material: water and air cannot pass through or circulate within the foam. In open-cell foam, the cells are interconnecting bubbles which can allow water or air in: the sponge in your sink is a good example of an open-celled foam. Closed cell foams won't compress as much as open-cell foams because the air cannot escape the base material; even the softest closed-cell foams are firmer than open cell foams. The use of open-cell foams in areas that might get exposed to water, either from perspiration or the weather, is problematic: even when encased with "water-proof" fabric, open-cell foams can be hydrophilic and actually draw moisture in from the environment.

Poron® is an exception to many of the rules: it is a poured urethane foam that is very dense and yet very soft; though it is open-cell, it absorbs very little moisture. Poron® is generally too heavy for extensive use on a bag, but wrapped in fabric it makes a great handle. Cushy and inviting to the touch, it has phenomenal resilience and won't break down or go flat over time.

Meshes and Knits

There's a huge variety of knit fabrics and meshes used in the bag and backpack industry. Open- and closed-cell foam can be laminated to stable warp knits and stretchy Raschel knits of polyester, nylon, and nylon/lycra blends to create composite materials with unique properties.

Brushed polyester tricot laminated to soft open-cell foam provides good protection for electronics with very little weight.

Polyester and nylon meshes lend visibility to a bag's pockets and breathability to surfaces that make contact with the user: 3D Spacer Mesh is a polyester/nylon blend that can help transport moisture and heat away from the contact areas on the panel against your back.

Organic Cotton

We are introducing a number of our bags made in cotton fabric — a more natural alternative to our usual nylon fabrics. Cotton canvas was the go-to fabric for bags and backpacks for decades prior to the introduction of nylon fabrics by the military in the early 1940s. Though synthetics fabrics are definitely longer lived materials (sometimes to the detriment of the environment), cotton has a certain aesthetic charm unmatched by synthetic materials.

Broadly speaking, we are using two different cotton fabrics: lighter cotton twills or ripstops similar to what the U.S. military uses in clothing/pants; and a heavier canvas, woven in the U.S. of organically grown cotton from Texas.

The lighter cotton is a good choice if you’re looking for a tote bag that can be folded or rolled into the smallest space — to be carried along in your car or luggage, ready for use. The heavier cotton has more body: it doesn’t compress as small as the ripstop fabric will, but it will stand up at the grocery checkout or your kitchen counter. While the heavier cotton canvas will last longer than the lighter ripstop, you can expect both of them to wear out sooner than our nylon bags. By no means is a TOM BIHN tote bag made of cotton a single-use, disposable product: you can still expect years and years of use from it, though perhaps not decades.

Thread

Nylon thread stretches with nylon fabric, and that's a good thing for final assembly seams and high stress areas. However, nylon thread requires an added binding agent (typically synthetic wax) to make it sewable. This wax often oxidizes (whitens) as it ages, which makes the thread stand out against the fabric, especially black thread on black fabric.

Polyester thread is excellent for exterior stitching because it fares better than nylon when exposed to sunlight, and produces a slightly neater stitch. Lacking the binding agent that nylon thread requires, its color remains stable over time.

Both nylon and polyester thread are available in different nominal sizes or weight; the bigger the number, the thicker the thread. In general, two rows of thinner thread are better than a single row of thicker thread, as one row can fail and the seam will still remain intact and functional.

We use different weights depending on the needed strength: nominally Tex 40 (pre-assembly over-lock); Tex 60 (labels, zippers and exterior top-stitching); Tex 70 and Tex 80 (final assembly, bar-tacking, etc.).

Our thread is made both in the U.S.A and in Germany. Like all of our components, we buy the best regardless of price.

Finally, seam failure in our bags is almost unheard of: properly stitched, the actual sewing is stronger than the fabric, the zippers and the buckles. If any thread or stitching on your TOM BIHN bag ever fails, we've almost certainly done something wrong, and we will fix it or replace it free of charge.

Zippers

There are two primary types of zippers used in outdoor and travel gear these days: coil and molded tooth.

We use mostly coil zippers on our bags and backpacks. Coil zippers are made by sewing an oblique coil (imagine, if you will, a flattened-out spring or Slinky) onto the edge of lightweight webbing (tape). The coil is shaped to create the zipper's teeth. Two of these coil/tape assemblies joined together form a continuous length of zipper chain; we get ours from YKK® in 100 meter rolls.

Molded tooth zippers are more of what people imagine when they think of a zipper: individual teeth are molded in series onto the edge of the tape. Each of these styles have advantages and disadvantages. Significantly, coil zippers tend to operate more smoothly, especially when going around curves and corners (our bags tend to have lots of curves!); tooth zippers tend to bind up and jam when negotiating corners.

One instance in which tooth zippers excel is with separating zippers (like on the front of your jacket): the separating mechanism itself is the same plastic as the teeth and is molded into the zipper tape, which allows for very tightly engineered tolerances, and therefore excellent alignment of the zipper teeth when you're starting the zipper. With a separating coil zipper, the mechanism is metal pressed onto the tape. The teeth don't always align perfectly when you're starting the zipper; additionally, the pressed-on mechanism tends to fail relatively early in applications that get a lot of use (like the front of your favorite jacket). Our designs don't use many separating zippers—if we use one and it's going to get lots of separating and un-separating (like on the Hero’s Journey), we'll use a tooth zipper instead of a coil zipper.

Zippers come in different gauges or tooth sizes, nominally measured as the width in millimeters of both halves of the zipper teeth when joined together: we use #3, #5, #8 and #10. We use the larger sizes (#8’s and #10’s) on the outside of most of our bags as they will last longest in these applications; #5’s are great for interior pockets and pouches, and #3’s are good when you’re really counting the ounces.

We've mostly transitioned from utilizing YKK® Aquaguard® water-repellent zipper in favor of YKK® Racquet Coil zippers with a water repellent treatment. To learn more about that transition, check out this blog post: Zipper Updates. So this is actually two changes at once: the zipper itself is changing, and the way the zipper is made water repellent is changing as well.

Racquet Coil (RC) zippers are coil zippers that are engineered by YKK to be tough and resist abrasion. An RC zipper looks almost indistinguishable from the standard coil zippers we’ve been using for decades: our best guess is that none of you would have noticed the change had we not pointed it out. The subtle but important difference is that on a Racquet Coil zipper, the thread that holds the continuous coil (which creates the “teeth” of a coil zipper) is recessed below the surface of the plastic coil itself; this is achieved by making the coil somewhat oblique in shape. Like a “racquet” in profile:

The second change is our moving away from the Aquaguard® urethane coating on the back side of zipper tape (the fabric part of a zipper) in favor of a durable water repellent (DWR) treatment on the tape of the Racquet Coil zipper. While folks have always appreciated how water repellent our bags are, some folks weren’t fans of how the Aquaguard® zippers require a little bit of an extra tug to open and close due to the thickness added to the zipper tape by that urethane coating. In our own tests, we found that the water repellency of the Racquet Coil zipper treated with DWR to be on par with that of the standard coil Aquaguard zippers. (Note that YKK applies the DWR to our Racquet Coil zipper on special order – Racquet Coil is not water repellent by nature.) And, since the Racquet Coil zippers are smoother to zip open and shut than Aquaguard®, the transition to Racquet Coil seemed like a no brainer to us. Some folks may still prefer Aquaguard®, some folks will be delighted by the transition to Racquet Coil, and probably most folks would appreciate either zipper, as both are high quality options.

Below is some additional information about Aquaguard® that we’d thought we’d keep around, just in case folks find it useful:

Aquaguard zippers have a urethane coating on the flat side that makes it highly water repellent (though not waterproof). When we first started using them, we did what other manufacturers did and sewed our Aquaguard® zipper in "upside down," that is, with the coating exposed. This has two advantages: first, the customer knows for sure that the zipper is coated because they can see the coating; and second, water is repelled before it can soak into the zipper tape. However, after doing this for several years, we saw that the urethane coating didn't last quite as long as we'd like when exposed to the wear and tear of the outside of a bag or backpack. In 2015 we started sewing Aquaguard® zippers in "right side up," putting the urethane coating on the inside of the bag (just as we do with our urethane-coated fabrics). You could still see the glossy coating—you just needed to look inside the bag.

One of the trade-offs of the Aquaguard® zipper is that it requires a little bit of an extra tug to open and close the zipper; this is due to the fact that the same urethane coating that makes the zipper water-repellent adds a tiny bit of thickness to the zipper tape, which creates a small amount of additional resistance. (It’s worth noting that the Aquaguard® zipper is far easier to open than the truly waterproof zippers found on bags designed to be 100% submersible in water.) Some folks don’t notice that little bit of extra resistance when zipping open their zipper while others do.

As mentioned above, when Aquaguard® zippers were first introduced, everyone sewed them in upside down (or backwards, or “reverse”). Nowadays, many manufacturers sew uncoated zipper chain into their bags (and jackets, etc.) upside down, utilizing the reverse zipper sliders originally developed for Aquaguard® zippers. We're not sure why this is done: maybe some folks think the flat side of the zipper looks cooler? One of the downsides to doing this is that it can confuse customers into thinking that the zipper is "waterproof" when it actually isn’t even particularly water repellent; a further complication is that there is now coated zipper chain available that is intended to look water repellent, but isn’t. An interesting side note: coil zippers are engineered to best bend around corners and curves when the teeth are on the outside of any curve, and so sewing any zipper that curves or bends in an up-side-down or reverse orientation will theoretically cause the zipper to wear out prematurely.

The gizmo on the zipper that opens and closes it is called the slider; the thing on the slider that you grab onto is called the pull. We designed a special “medium” length zipper pull because we didn’t like YKK®’s long pull nor their short pull; like Mama Bear, we wanted the one in the middle that was just right. Our metal zipper sliders are made of zinc alloy and are plated to look nice and resist further oxidation. On many lighter-duty applications we use a molded plastic slider: it won’t scratch sensitive electronics and also won’t trigger a metal detector (important for items like our Travel Money Belt). We’ve been impressed with the durability of these plastic sliders and have seen virtually no failures. Our bigger bags now come with a generous supply of cord zipper pulls which you can add to your bag yourself if desired. There's a video here that show you how to add them.

We use YKK® zippers exclusively—they’ve been at it for a long time and they know their stuff. We could save a buck or two going with a generic zipper.... but after all we do to make the best bags, that would be silly!