My train rolled along tracks winding though a landscape dotted with farms and the steady rattle was punctuated by the assault of raindrops and gusting wind against the windows. We had just pulled out of a station and the new passengers, with a cold dampness clinging to them, fled into our car.
One man in particular was lightly dressed and was drenched. As he settled into a seat, the reason for his condition became clear - he carefully unfolded a ball, which he had painstakingly shielded with his body, revealing a beautiful suede jacket.
Amused, I turned to see some cows slowly grazing in the rainy landscape. Clearly they did not check the weather forecast but they didn't seem to be nearly as worried about ruining their leather coats.
The irony was hard to miss. I doubt a caveman ever took off his animal skin to protect it from rain. Yet after thousands of years of progress, we're all checking weather forecasts before we use our precious leather goods outdoors.Somehow, we'd evolved from the protected to the protector.
How, I thought, can we reverse this absurd trend? Is it possible to make leather so that we can once again use the material to protect us from the elements and physical assaults of daily life - so we don't take off our dress gloves to clear snow from our car? Can we make leather less fragile? Can we let the elements abuse our leather, without losing the aesthetic look, feel and comfort which enticed us to buy it in the first place?
With these thoughts as inspiration, my fellow DuPont scientists and I set out in search of technologies to make using leather more worry-free, so that we could all use and enjoy our leather products with confidence.
Our goal was to bring together a suite of attributes that had never been available together for leather:
- Weather-resistant: Leather that repels water - making it safe to wear even in the worst weather conditions
- Fast drying: Leather that resists water absorption and dries in a fraction of the time of conventionally tanned leather - yet is still soft and supple and without water marks after drying
- Washable and dryable in household appliances: Leather that is convenient to use and easy to care for
- Fit memory: Leather that allows products to retain their original fit
- Colourfast: Leather that features colours that resist bleeding or fading as the leather becomes wet or is laundered
- Breathable: Leather that provides excellent air moisture management and comfort
- Aesthetics: Leather that has the touch, scent and look of natural leather, unadulterated by polymer films
- Stain and soil-resistant: Leather that repels dirt, grime and water-based stains such as coffee, tea, fruit drinks, sodas and ketchup, so that stains wash out easily.
So we set out to capture all these attributes in leather by using a rational ‘building block' approach. We carefully chose re-tanning, fatliquoring and other chemicals to be introduced in specific sequences and under precise conditions.
Because this process lays a stable foundation upon which the subsequent chemicals interact synergistically with their predecessor(s), the resulting product is durable and stable. The desired properties are an intrinsic part of the leather produced.
This meant a lot of testing and lab work for each attribute that we sought:
Surviving a washing machine and dryer: We tested our product using AATCC and ASTM test methods for assessing the effects of home-laundering (AATCC TM135) - colourfastness (AATCC EP1), dimensional stability (ASTM D6013), dye transfer to multi-fabric test swatch (ASTM D2096) and hand (qualitative). The results were all very good.
Stain resistance: We tested for static water and oil repellency, as a measure of resistance to staining by water (AATCC TM193) or oil-based (AATCC TM118) liquids such as soda, coffee, wine and salad dressing. The results were excellent, even if the stains were forced into the leather (AATCC TM130). The test results for the release of the stains in laundering were also excellent, as was resistance to dry soil (AATCC TM123).
Protection against the weather: Over time, we learned and improved the formulations, as well as the assessment methods. For example, we began by using AATCC TM22 to assess the effect of simulated rain. However, this method mostly measures surface wetting.
In search of a more aggressive method, we settled on a textile simulated rain test method (ISO 9865) whose focus is more on water penetration. However, instead of ‘raining' on the test sample for ten minutes, we increased the exposure. We were very pleased that under these demanding conditions, there was essentially no water break-though, even after four hours!
Similarly, we use Maeser flex (ASTM D2099) and resistance to hydrostatic pressure to measure water penetration for different end-uses. In addition to staying dry (no water penetration), we believed low water absorption is important - soggy, heavy leather is a negative to the end-user.
Again, we found that this technology delivers outstanding results by either ASTM D6015 or as a part of ISO 9865 or ASTM D2099. Because of the nature of this technology, the low water penetration and absorption is not achieved at the cost of comfort: ‘Breathability' or water vapour permeability (ASTM D5052 or Satra methods) is not compromised.
Another benefit is the speed of drying. As one can imagine, a very hydrophobic leather that has low water absorption would not ‘hang on' to water and such a leather would dry fast. This trend was confirmed in our testing (using an internal DuPont test method).
Voice of our customers
In parallel to our efforts to improve our technology, we worked on implementation, demonstrating production capabilities at a number of tanneries for a variety of types of leathers. We also engaged manufacturers, designers and brand houses to produce sample goods and solicit their feedback: Here's what they told us:
- Providing comfort by keeping the user dry - while maintaining the article's breathability - is important for apparel (eg outerwear, hats/caps), gloves (outdoor, ski, hiking, military, tactical, gardening, dress) as well as footwear (outdoor, hiking, military, tactical, dress). The convenience of fast drying is also important for the above end-uses
- For performance goods such as athletic gloves, footwear and equipment (golf, soccer, baseball, football, track and field, hockey), lower weight - thanks to less water absorption - would likely give athletes an edge. A product's ability to be comfortable and fast-drying are also valuable to athletes
- Remaining supple and comfortable even after extended exposure to water is important for any application where the goods are exposed to the elements (sports or outdoor shoes, or gardening gloves) or sweat (sports gloves). No one likes to wear stiff gloves or shoes
- Providing protection is important for accessories (papers in a briefcase,computer in a backpack, cheques in a purse or handbag, or an iPod in its case)
- The convenience of easy-care is becoming more valuable. Consumer goods such as apparel that resist soiling and staining (looks good longer) and is easier to clean (home laundering and stain-release) provide that convenience as well as peace of mind.
Once we succeeded in packaging these attributes into one technology, we had to find a name for it. So we engaged in a naming study and creative process to position the new offering. The name tested well with our partners and customers. Hydrology was ‘born' because it denotes the ‘science dealing with the occurrence, circulation, distribution, and properties of water...' (dictionary.com).
From casual observations and bemusement that turned into inspiration and a lot of hard work (and perspiration), we believe we accomplished our goal. DuPont science allows consumers to wear leather in any weather. The attributes are derived from the retanning process and are incorporated into the core of the leather; therefore they are intrinsic and durable.
DuPont Hydrology employs a total systems approach to tanning the leather and delivers a deep penetrating protection against weather, nature's elements, stains and soil. Available today for jackets, it will soon be used in a wider variety of leather products including coats, hats, gloves, shoes, boots, briefcases, luggage, handbags, furniture and pillows.
Because of the large number of benefits offered by this technology, manufacturers and brands can select the benefits most important to their specific application. For designers, it presents possibilities for which leather is not historically used - eg swimwear, casual-wear, and trims and accents with fabrics. For consumers, this could also represent cost savings from longer product life, greater utility and lower maintenance spending.
Perhaps, most importantly, Hydrology gives peace of mind knowing we can wear our leather in the rain, no longer having to envy cows or cavemen.