To harden leather, you have to change its structure at the molecular level of the material. This is usually done by combining heat with water or wax, but there are several ways you can choose to do this.
Step
Method 1 of 3: Soaking with Water
Step 1. Soak the leather in cold water
Fill a large bucket or sink with cold or room temperature water. Soak the skin in the water for about 10 minutes, or until completely wet.
- Keep in mind that this process has the best results when performed on vegetable cowhide.
- You can actually harden the leather by simply soaking it in room temperature water, but it's only slightly harder and you can't shape it. The additional step with hot water will allow you to make changes to the skin's structure while hardening it.
Step 2. Heat the second pot of water
While your skin is soaking, fill a large pot with water and heat it on the stove over high heat. Continue heating the water until it reaches 82 degrees Celsius.
- Use an accurate thermometer to check the temperature of the water. If the water becomes too hot or too cold, the results will vary widely from those described in this article.
- If you don't have a thermometer, you can measure the temperature of the water by gently heating it on the stove and testing it every minute with your hand. If you can put your hand in water, then that temperature can be used for your skin. When you can't keep your hands in the water for a long time, remove them from the stove and don't continue to heat them.
- Some people choose to soak the skin in boiling water. This will harden the skin more quickly, but you won't have much room to shape it. As a result, the skin will become brittle and unevenly hard on the surface.
Step 3. Dip the skin in hot water
Pull the skin out of the cold water and submerge it in the hot water. Let it soak for a few minutes.
- After the first minute, you will be able to see your skin start to darken and curl.
- The longer you soak the skin, the tougher it will be. If you soak your skin for too long, it will become more brittle as it dries.
- Using this method, soaking the leather in hot water for 30 seconds after it has darkened will result in a piece of leather that is firm but not too hard. This means that you have 90 seconds to soak your skin in hot water. Leave the leather in hot water longer if you want a tougher leather.
Step 4. Shape it the way you want
When you remove the leather from the water, you will have leather that is still quite flexible. If you need to shape it to a specific shape, now is a great time to do so.
While wet, the skin will stretch and can be easily molded. This suppleness will go away in a minute or two, so you'll need to work on it quickly if you want your leather to stretch a little. The leather will still be malleable for an hour after it can no longer stretch
Step 5. Let the leather material dry at room temperature
Dry the skin at room temperature for a few hours. Once dry, your skin will become hard and stiff.
The toughened skin will also shrink, so the pieces you had at the start will look smaller once this process is complete
Method 2 of 3: Baking
Step 1. Soak the leather in room temperature water
Fill a sink, bucket, or similar container with cold water to room temperature. Soak in water until the leather is completely wet.
- This process is generally recommended for use on vegetable cowhide.
- The length of time you soak the leather depends on the thickness and quality of the leather. Usually, just 10 to 30 minutes of soaking it will suffice. The leather will be quite flexible when you take it out of the water.
Step 2. Preheat the oven
While the skin is soaking, preheat the oven to 50 degrees Celsius.
- Move the rack in the oven to make more room for the skin pieces.
- If your oven cannot be set to this low, use the lowest temperature available in your oven. But keep in mind that higher temperatures can cause heat from the steam, and can change color and cause more shrinkage.
Step 3. Shape your skin as desired
Remove the skin from the water. If you plan to shape it, do so now, while the leather is still flexible and malleable.
Since the leather is still fairly cool at this stage, the shape you're making won't last very long when you take it off. Once you've shaped it, you'll need to keep it in shape using string, stitches, or nails
Step 4. Bake your skin
Place the moist, molded skin in the oven and bake until dry. Depending on how long you soak it in the water, this can take anywhere from 20 to 90 minutes.
You can leave the leather in the oven even after it dries, but remember that baking it dry will increase the temperature of the leather and the leather will become tougher and more brittle
Step 5. Cool
Remove the hot, dry skin from the oven and cool to room temperature until it is safe to hold in your hands. At this time, the leather material will continue to harden.
Once cool, you'll need to remove any thread, string, or nails holding the shape. When the leather material has become hard enough, the new shape will be well preserved
Method 3 of 3: Layering with Wax
Step 1. Preheat the oven
Set your oven to 90 degrees Celsius and let it heat up.
- Make sure that the racks in the oven have been removed and arranged in such a way that the leather will fit in without coming into contact with other racks or with the sides of the oven.
- This method will work with other leather types, but plant-based leather is still the easiest to shape. Also keep in mind that this is a good method to use if you want to harden skin that has been molded and doesn't require additional shaping.
Step 2. Dry roast the skin
When the oven is hot enough, add the skin and bake for 30 minutes. The leather will be hot to the touch when you remove it from the oven.
- The heat itself is an important part of this hardening process. In essence, the heat melts the molecules in the skin, causing the molecules to break down and making the skin more supple. When the molecules refreeze, they form a structure that is much tougher than the original chemical structure of the leather.
- If you leave the skin too hot, it will cause the skin to become brittle.
Step 3. Melt a little wax
Place a piece of beeswax in a double team pot and heat until melted. Do this while the leather is baking so the skin and wax will be hot enough to do it at the same time.
- Beeswax is the wax of choice, but you can use any melted wax, too.
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To melt the wax:
- Heat 2.5 to 5 cm of water in a double bottom pan set on the stove over medium heat.
- Place the candle in the top double team pot.
- When the wax begins to melt, stir it with a spoon or disposable chopsticks. Continue until completely melted.
Step 4. Sweep the wax on the skin
Remove the skin from the oven and place it on a few valleys of newsprint. Use a large paint brush and apply the hot wax to the hot skin evenly.
- The skin will be wet with the hot wax. If not, then the skin is not hot enough and should be returned to the oven.
- Continue rubbing the wax over the skin until the skin has cooled and cannot absorb the wax.
Step 5. Heat and brush the wax back if needed
After the first coat of wax, return the skin to the oven and preheat for about 20 minutes. Remove from oven and brush again with an additional layer of melted wax.
- You'll need to repeat this process until your skin can no longer absorb the melted wax, even when it's hot.
- One way to tell if your skin can no longer absorb liquid wax is to look at the color. The wax will slightly change the skin tone. If the entire surface of the leather has an even color, then the leather has absorbed as much wax as possible on the entire surface.
Step 6. Cool completely
Allow the skin to cool and dry completely. When finished, the skin will be very hard and will not be able to bend.
