what to use to stiffen leather?

[mrdabeetle]

I know a guy who swears that soaking the leather in urine (Eeeew!) will harden the leather and will last a long time. I am not willing to test his theory, but I suppose the ammonia is what does the hardening.

I have tried the diluted white glue method with great results. I have also tried adding alcohol to your water when wet forming works as well. Be sure to burnish or round the edges in some way before hardening. Some corners can get very sharp if you don't. A vendor at a recent festival had some masks that were uncomfortable to wear because the edges were not rounded off.

Another way to harden is to spray a clear acrylic sealer inside and out. It basically turns the leather into a rubbery material that will hold it's shape well. It works on masks, but I haven't tried it on anything else.

[712Gear]

I am wet molding a project (bag) and want to apply something to it to stiffen it so it wont lose it's shape while being used. any ideas? was wondering about gluing a fabric liner to the inside would the glue stiffen it?

Scott

First background on what makes leather soft

Leather from the tannery is soft and supple b/c as part of the process they treat it with oils which absorb into the leather. These oils are not volatile meaning they are slow to evaporate so the leather will stay soft for years. But over time if not reconditioned the leather will harden. Now the oils they use and how they do it, is a highly protected secret. Every tannery does this different resulting from years of experience this is why good leather comes from old tanneries. Regardless of the intricate details of the process they all involve large tumblers most made of wood. I would guess the tumbling action would be to work a hydrophobic material(oil) into wet (hydrophyllic) leather. The process is similar to putting conditioner in your hair or rubbing lotion on your skin. The old time mountain man way involves a lot of manual pulling and rubbing.

What makes leather rigid

Any solvent that extracts(removes) this oil from the leather will stiffen it. Hot water, warm water, cool water, water with soap are all good. Just think to yourself will this remove oil? Even urine b/c it has ammonia which leads me to yes ammonia will remove oil, that's why it's such a good cleaning solvent. No time to wait for drying use 70% IPA(isopropanol or rubbing alcohol). The question is how much to soak for how long in what solvent? This is up to you to experiment with, to come up with your own secret process. This is part of the art after all.

Other thing to consider

Fiebing prep & dye cleaner is ~97% ethanol 3% Ammonia by volume. This is to remove the oil in order for the water soluble dye to absorb. Companies have to tell what their solvent are in their MSDS, Fiebings prep is here -> http://siri.org/msds/f2/cgq/cgqdw.html

Water soluble dyes will stiffen leather, oil dyes not so much

Leather that is too stiff becomes brittle and will break and tear easier, find the happy medium if you need your project to stiffen up

Leather cleaners and conditioners work b/c they put oil back into the leather.

Oil in the leather fills the pores, when the oil is extracted and replaced with a volatile solvent(water, ethanol, IPA etc) these spaces collapse. This is what makes the leather shrink.

Elmers glue diluted in water - awesome idea but elmers glue dissolves in water after it cures so if the mask gets wet some thin fine cuts may start to bend. Water proof wood glue (not the polyurethane type) is water resistant after it cures.

hope this helps!

-db

[Randy Cornelius]

Weaver Leather makes a comerical product called, "Leather Stiffner" I have used it and had average results. Not sure what's in it but it is clear and buy it by the gallon. I use it on molded items.

RC

[kschmadeka]

I realize I'm late to this conversation but thought I'd post my stiffening process that I use for my wallet holsters.  Of course the holsters I make are a simple flat leather flap so anything fancier might need some adjustments to the process.  I don't remember where I saw it, but in searching for info on stiffening I read about how a combination of soaking and heat will cause the oils in veg-tanned leather to break down under heat and then resolidify as it cools into a harder more plastic-like substance, stiffening the leather.  So here's the process that works for what I do.

First, dye the leather with professional oil dye.  Other dye's won't work as well.  Let the dye dry for at least a day so it's fully dry.  Preheat your oven to about 250 degrees.  Have a large cookie sheet inside with some kind of pine wood rack to hang your leather on (but don't preheat the rack too much before use.)  Soak the leather in warm water for five minutes and do the wet-forming.  Put it in the oven on its rack and watch it closely.  It takes 8 to 12 minutes depending on the thickness of the leather and brand.  The tricky part here is that the point where it's properly stiffened is not long before the point where it's ruined.  So practice on scraps, see how long it takes for them to wrinkle up, and plan on adjusting your heat and time so it can cook about 10 minutes without frying.  If you see any wrinkling, grab it out and you might still be able to save it, but ideally there won't be any.

After it's cooked, take it out and clamp it into some type of molding device to hold the shape while it cools and the plastic substance forms.  After it's cooled, hang it up to air dry, which usually takes about a day, or less if you use heat or a fan. 

The most frequent complaint about my wallet holsters is that they're too stiff, and I keep having to explain that they have to be made that way to work right.  This process also makes leather a lot more cut-resistant, so I think it would work great for leather armor too. 

[Kristina]

On 4/29/2009 at 6:57 PM, outcast said:

Soak it in water mixed with ammonia (1 gallon/1 cup), wet mould, let dry. It's worked for me before.

Do you have any thoughts about how much dye will be removed from the leather piece if I dye the leather first (with Tandy Professional Eco-Flo Water Stain), dry, then soak in ammonia/water solution?

[Pdxgtigirl]

On 10/14/2017 at 5:43 PM, kschmadeka said:

I realize I'm late to this conversation but thought I'd post my stiffening process that I use for my wallet holsters.  Of course the holsters I make are a simple flat leather flap so anything fancier might need some adjustments to the process.  I don't remember where I saw it, but in searching for info on stiffening I read about how a combination of soaking and heat will cause the oils in veg-tanned leather to break down under heat and then resolidify as it cools into a harder more plastic-like substance, stiffening the leather.  So here's the process that works for what I do.

First, dye the leather with professional oil dye.  Other dye's won't work as well.  Let the dye dry for at least a day so it's fully dry.  Preheat your oven to about 250 degrees.  Have a large cookie sheet inside with some kind of pine wood rack to hang your leather on (but don't preheat the rack too much before use.)  Soak the leather in warm water for five minutes and do the wet-forming.  Put it in the oven on its rack and watch it closely.  It takes 8 to 12 minutes depending on the thickness of the leather and brand.  The tricky part here is that the point where it's properly stiffened is not long before the point where it's ruined.  So practice on scraps, see how long it takes for them to wrinkle up, and plan on adjusting your heat and time so it can cook about 10 minutes without frying.  If you see any wrinkling, grab it out and you might still be able to save it, but ideally there won't be any.

After it's cooked, take it out and clamp it into some type of molding device to hold the shape while it cools and the plastic substance forms.  After it's cooled, hang it up to air dry, which usually takes about a day, or less if you use heat or a fan. 

The most frequent complaint about my wallet holsters is that they're too stiff, and I keep having to explain that they have to be made that way to work right.  This process also makes leather a lot more cut-resistant, so I think it would work great for leather armor too. 

Thank you for the information. I’m going to try this soon.