What Is EVA Foam?

Ethylene vinyl acetate (also known as EVA) is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene.
It is a polymer that approaches elastomeric materials in softness and flexibility, yet can be processed like other thermoplastics. The material has good clarity and gloss, barrier properties, low-temperature toughness, stress-crack resistance, hot-melt adhesive water proof properties, and resistance to UV radiation. EVA has little or no odor and is competitive with rubber and vinyl products in many electrical applications.

Applications

Hot melt adhesives, hot glue sticks, top of the line soccer cleats, are usually made from EVA, usually with additives like wax and resin. EVA is also used as a clinginess-enhancing additive in plastic wraps.
EVA is also used in biomedical engineering applications as a drug delivery device. The polymer is dissolved in an organic solvent (e.g., dichloromethane). Powdered drug and filler (typically an inert sugar) are added to the liquid solution and rapidly mixed to obtain a homogeneous mixture. The drug-filler-polymer mixture is then cast into a mold at −80 °C and freeze dried until solid. These devices are used in drug delivery research to slowly release a compound. While the polymer is not biodegradable within the body, it is quite inert and causes little or no reaction following implantation.
EVA is one of the materials popularly known as expanded rubber or foam rubber. EVA foam is used as padding in equipment for various sports such as ski boots, bicycle saddles, hockey pads, boxing and mixed martial arts gloves and helmets, wakeboard boots, waterski boots, fishing rods and fishing reel handles. It is typically used as a shock absorber in sports shoes, for example. It is used for the manufacture of floats for commercial fishing gear such as purse seine (seine fishing) and gillnets. In addition, because of its buoyancy, EVA has made its way into non-traditional products such as floating eyewear. It is also used in the photovoltaics industry as an encapsulation material for silicon cells in the manufacture of photovoltaic modules. EVA slippers and sandals are currently very popular because of their properties like light weight, easy to mold, odorless, glossy finish, and cheaper compared to natural rubber. In fishing rods, it is used to construct handles on the rod-butt end. EVA can be used as a substitute for cork in many applications.
EVA emulsions are polyvinyl acetate (PVAc) copolymers based on vinyl acetate (VAM) internally plastized with vinyl acetate ethylene (VAE). PVAc copolymer are adhesives used in packaging, textile, bookbinding for bonding plastic films, metal surfaces, coated paper, as redispersible powder in plasters and cement renders
Vinyl acetate ethylene copolymer(VAE), is also used in coatings formulation of good quality interior water-borne paints at 53% Primary dispersant
Hydrolysis of EVA gives ethylene vinyl alcohol (EVOH) copolymer.

Other uses

EVA is used in the manufacture of the Adidas Jabulani football. EVA is used in orthotics, fire safe cigarettes (FSC), surfboard and skimboard traction pads, and for the manufacturing of some artificial flowers. It is used as a cold flow improver for diesel fuel and a separater in HEPA filters. EVA can easily be cut from sheets and molded to shape. It is also used to make thermoplastic mouthguards that soften in boiling water for a user specific fit. It is also used for impregnation of leather. Additional uses are in the making of nicotine transdermal patches since the copolymer binds well with other agents to form gel like substances. EVA is also sometimes used for making body bags.

How to Clean Leather

Steps to Cleaning Leather

First, get your supplies together: you'll need gentle hand soap (in the interest of keeping this project green, I grabbed a bottle of Method Hand Wash out of my bathroom), olive oil, and a few soft, clean rags. You'll need water, too, but you can get that straight from the tap. Then, before you jump into cleaning your whole couch or that stain on the front of your jacket, it's important to test the cleaning method from start to finish in a small, hidden place, just to make sure it won't lighten, darken, or dry your specific piece of leather. 

Once you're ready to get started, you'll need to prepare a rag by dampening it and applying a little soap. Get the whole rag wet if you're cleaning a large area, but for small stains it should be sufficient to run a corner of the rag under the tap. Either way, remember that the rag should be just slightly damp, not soaking wet; squeeze out any excess water before pumping a small amount of hand soap onto the rag. 

Rub the rag against itself a little to work the soap into the cloth before you begin cleaning. You don't want to apply a glob of soap to a piece of leather. Instead, gently rub a light lather onto the leather until it appears clean. 

Next, slightly dampen another rag to wipe any soap residue from the leather. Because even finished leather is not completely water-repellant, you should never rinse it with a very wet rag or by running water directly over it. Using a rag with a minimal amount of water on it protects the leather from absorbing enough water to become damaged. 

Use a dry rag to remove the light film of excess water that may be on the surface of the leather after rinsing. Before moving on to the next step, it's a good idea to also let the item sit for a few minutes to air dry in case the leather has absorbed water during cleaning. 

Finally, you should always condition leather after cleaning, since the soap will have removed some of its natural oils. This is where the olive oil comes in. Put a very small amount of olive oil on a dry cloth and rub it into the leather. Using too much oil will make the leather greasy or sticky and attract dirt, so it's crucial to apply only a tiny amount; if the leather is darker or shinier after oiling, you've used too much. I was very happy with this method of cleaning leather; when I finished, my jacket looked exactly the same—except, of course, it's clean now.

Buying Eco-Friendly Leather

Leather is a natural product, right? Well, not so much anymore. Animal hides provide the raw material for leather, but that's where "natural" ends and "environmental nightmare" usually begins. And "natural," unfortunately, is not synonymous with "cruelty-free." Animals raised for leather live in the same deplorable conditions as animals raised for meat—and they aren't necessarily the same animals. That means leather products are not simply a conscientious use of the skins of animals that were going to be eaten anyway. Then, once the hides enter the tanning and finishing process, they are bombarded with acids and decidedly unnatural chemicals. The leather-making process uses large quantities of fossil fuels, contributes heavily to greenhouse gas emissions, and creates wastewater full of sulfides, heavy metals, and carcinogens.
Fortunately, though, some leather companies are making an effort to limit their environmental impact. For most, that means using alternative energy sources, tracking their greenhouse gas emissions, recycling water needed for production, treating wastewater before releasing it into the environment, and using leather pieces that would otherwise be wasted. One company, Organic Leather, bases its entire business on being environmentally friendly. They only use recycled leather and hides from animals that were raised organically or on family farms for the meat industry, and instead of chemicals, they process the leather with smoke or natural tannins and oils. These processes are drawn from traditional leather making and provide a rare opportunity to use leather products guilt-free.

Natural Leather Cleaners

Montana Pitch-Blend offers a range of products for various leather cleaning and conditioning situations. I like this company because they divulge their ingredients clearly and without hesitation, and those ingredients are primarily pine pitch, mink oil, and beeswax. 

Leather Mate is a one-step leather cleaner and conditioner made from lanolin, carnauba wax, and other natural compounds. It's a biodegradable product with a 50-year history. 

Oakwood Liquid Leather Cleaner and Leather Conditioning Cream are Australian products containing an array of natural oils and waxes, including tea tree oil, beeswax, eucalyptus and emu oil (who knew?). These sound like they would make your leather both look and smell pretty.

Shoe Material

A broad spectrum of materials and material combinations are used today in shoe manufacturing. Leathers, synthetics, rubber and textile materials are counted among the basic upper materials. Each material has its own specific character and they differ not only in their appearance but also in their physical properties, their service life and treatment needs. The choice of shoe material significantly influences the life of the footwear, and in many cases dictates its use

PVC, PU, rubber, leatherette and polymeric materials all have a similar look as leather but the characteristics of breathing, absorption, and flexibility do not measure up to the qualities of natural leather.

New upper materials in PVC and PU combined with comfortable linings do offer a few advantages however: namely affordable low prices; and a multitude of colour choices, shapes and designs- especially in young fashion.

Polymeric synthetic leathers are synthetic hides, which mimic natural hides in both appearance and physical characteristics. When compared to natural leather, synthetic hides are much easier to care for.

Rubber based uppers are used for special safety work boots. Textiles both natural or synthetic combined with rubber materials are used extensively in safety and casual footwear.

Waterproof membrane is a special material which provides water resistance and breathability to footwear (for example Gore-Tex); It is a major element in hiking and sport footwear.

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Leather

Leather is the most used natural material, and presents ideal characteristics for footwear. Leather breathes, it is soft, offers very good absorption ability; and is able to adjust to the individual shape of foot. We recognize several basic types of leather.

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Upper material

Leather The best upper material; natural, breathable and flexible; Having better strechabilty and adjusts to feet easily. Textile Characterized by a wide colour selection and lightness; used mainly for casual footwear. Synthetic Used for a wide spectrum of shades, easy to care for, suitable for rainy weather.

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Lining material

Leather Hygienic, comfortable and flexible. Textile Suitable for winter footwear because of its good thermal insulation qualities. Synthetic Easily cared for, easily put on; limited airflow which can cause higher perspiration.

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Sole material

Leather Has an elegant look, is light; solely designed for interiors; scrapes off easily; not suitable for wet conditions. PVC widely used as sole in various kinds of footwear mainly due to price benefit. It has moderate flexibility and abrasion.

Rubber has very good anti skid property and resistance to wear. Widely used for safety and sport footwear.
Synthetic Flexible, easy to care for; average resistance to wear; average thermo insulation qualities; slips in difficult terrain; not overly flexible.

(sumber : bata.com)

Sejarah Singkat Tentang Alas Kaki

Model Sepatu Primitif

Dari dulu, nenek moyang kita sudah memanfaatkan sepatu untuk dijadikan alas kaki. Hal ini terjadi, karena mereka sudah memikirkan tentang efek-efek besar jika tidak memakai alas kaki. Misalnya, saat berburu, menginjak bebatuan yang kasar dapat melukai kaki dan lain-lain, akhirnya mereka menciptakan alas kaki berupa sepatu untuk melindungi kakinya. Bermula dari zaman es atau 5 juta tahun yang lalu, sepatu di buat dari kulit binatang. Sepatu ini di temukan temukan dalam jumlah besar di Pedalaman Missouri, Amerika Serikat. Di perkirakan sepatu tersebut berasal dari 8000 SM. Selain di Amerika Serikat, di Pegunungan Perancis juga di temukan sepatu yang diperkirakan berasal pada tahun 3300 SM. Lama kelamaan, rerumputan dan semak juga dapat di manfaatkan sebagai sepatu. Rerumputan dan semak berguna untuk melindungi dari sinar matahari dan dinginnya suhu. Sepatu ditemukan juga di Mesir Kuno, Viking, dan China Kuno.

Di Mesir Kuno, terlihat dari lukisan di Thebes, Mesir, bahwa orang Mesir telah mengenakan alas kaki sekitar abad ke 15 SM. Lukisan ini menggambarkan pengrajin yang sedang duduk di kursi pendek. Seorang perajin sibuk membuat sandal dan terdapat juga pengrajin lainnya yang sedang sibuk memjahit sepatu. Sandal dan sepatu pada saat itu di buat dari kain, daun palem, papirus, kulit atau bahan serupa yang dianyam. Di Mesir, sepatu merupakan benda yang menunjukkan status sosial. Biasanya yang menggunakan sepatu adalah orang-orang kaya. Untuk Raja mesir, sepatu yang digunakan merupakan sepatu yang di lukis dengan indah.

Calceus (Sebutan Sepatu dari orang Mesir Kuno)

Pada masa Yunani dan Romawi Kuno, alas kaki merupakan salah satu penunjang kegiatan sehari-hari mereka. Alas kaki juga merupakan suatu gaya busana elegan bagi mereka. Pada saat itu, banyak jenis alas kaki yang di gunakan oleh mereka. Berikut adalah jenisnya:

1. Baxa atau Baxaea: Sandal yang dibuat dari anyaman daun palem. Biasanya, sandal ini digunakan oleh kalangan bawah dan pendeta. Sandal ini juga memiliki kemiripan dengan sandal orang-orang Mesir kuno (di tulis oleh Apuleius). Pengrajin sendal di sebut baxearii / solearii.
2. Solea: Alas kaki ringan yang dipakai di dalam rumah
3. Calceus: Alas kaki yang dipakai di luar rumah
4. Soccus: Alas kaki yang menutupi bagian atas kaki. Di gunakan di dalam rumah sebagai slipper atau selop di kebudayaan Barat.
5. Cothurnus: Sepatu boot yang menunjukan semua jemari kaki. Cothurnus juga di buat lebih tebal dengan gabus untuk kebutuhan penunggang kuda, aktor drama tragedi, pemburu, dan bangsawan yang ingin terlihat gagah dan tinggi.
6. Caligae: Sepatu dari tali yang talinya sampai mengelilingi betis.

Di jaman Yunani dan Romawi Kuno juga terdapat ciri khas jenis sepatu (caligae). Sepatu mereka terdapat tali-tali yang mengelilingi betis. Biasanya setelah peperangan dan mengalami kemenangan, para prajurit menempelkan paku dari perunggu, perak atau emas pada sepatu mereka.

Caligae 1

Caligae 2

Caligae di Meseum Arkeologi Perancis