The "Tornister-Lexikon für den Frontsoldaten" by Gerhard Bönicke was a book filled with handy tips for living in the field. Originally commercially published in 1942, it was re-published by the Wehrmacht and distributed to soldiers in 1943. Here are instructions for how to take care of shoes and boots.
"Shoe care
Proper care extends the life of shoes and protects against foot pain and blisters. After wearing shoes, either put them on supports or stuff with hay, straw, or newspapers. Never dry wet shoes on the stove or on the oven, this makes the leather hard and brittle, always keep them at least 1 meter from heat sources. Don’t put wet shoes on their soles, rather lay them on their sides or hang them up, so the soles can also dry. Regularly clean shoes inside and out. Clean the outside with a dirt brush and a wooden stick, and after drying, rub shoes and boots with leather fat or a fat-containing shoe cream. Rub in leather fat vigorously. Pay special care to greasing seams. Don’t overdo greasing, too much fat makes leather spongy, water-permeable, and causes cold feet. With marching boots, clean the shaft and upper, add fat (grease) to the lower. If you don’t have leather fat, use cod liver oil or castor oil. Avoid hardening oils (varnish) at all costs, as well as mineral fats and oils (vaseline oil). Regularly rub the insides of shoes and boots with a damp cloth or with a rag with methylated spirits. Always deal with small damages immediately.
"Shoe care
Proper care extends the life of shoes and protects against foot pain and blisters. After wearing shoes, either put them on supports or stuff with hay, straw, or newspapers. Never dry wet shoes on the stove or on the oven, this makes the leather hard and brittle, always keep them at least 1 meter from heat sources. Don’t put wet shoes on their soles, rather lay them on their sides or hang them up, so the soles can also dry. Regularly clean shoes inside and out. Clean the outside with a dirt brush and a wooden stick, and after drying, rub shoes and boots with leather fat or a fat-containing shoe cream. Rub in leather fat vigorously. Pay special care to greasing seams. Don’t overdo greasing, too much fat makes leather spongy, water-permeable, and causes cold feet. With marching boots, clean the shaft and upper, add fat (grease) to the lower. If you don’t have leather fat, use cod liver oil or castor oil. Avoid hardening oils (varnish) at all costs, as well as mineral fats and oils (vaseline oil). Regularly rub the insides of shoes and boots with a damp cloth or with a rag with methylated spirits. Always deal with small damages immediately.
Soles in completely dried out condition should be rubbed with varnish or linseed oil, until the soles are saturated. This makes soles durable and waterproof. Replace lost hobnails immediately. Rub moldy footwear with turpentine oil or turpentine oil substitute, or with lukewarm water mixed with soap or "Imi", this requires subsequent treatment with leather fat or a fat-containing shoe cream, dry well first.
Never apply fat to rubber shoes (fat destroys rubber), instead clean with a soft cloth with cold or lukewarm water (never use hot water!). To dry, hang up an ample distance from oven or stove.
Felt shoes should never be worn in wet snow and must be taken off as soon as they are soaked through, otherwise frost injury to the feet is unavoidable. Scrape and brush off coarse dirt, do not dry wet felt shoes too close to a heat source."
Never apply fat to rubber shoes (fat destroys rubber), instead clean with a soft cloth with cold or lukewarm water (never use hot water!). To dry, hang up an ample distance from oven or stove.
Felt shoes should never be worn in wet snow and must be taken off as soon as they are soaked through, otherwise frost injury to the feet is unavoidable. Scrape and brush off coarse dirt, do not dry wet felt shoes too close to a heat source."
