Scary Leatherworks

what to use to stiffen leather?

13 posts in this topic

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

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I did this to a set of saddle bags about ten years ago and there are still pretty stiff....first off the leather was 10oz.....when finished with construction, but before applying any oil or conditioner....I got them good and wet with hot water, then stuffed them with crumpled up newspaper then set them out in the sun to dry.

In this case I used Tandy's Super Sheen to finish....don't use it much anymore except on black dyed stuff....and to this day they are still pretty stiff.

I would expect, however that if the bag is used regularly, it will break down some in time.

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I know of a couple of people around here that make and sell leather masks (2-3 oz leather) that stiffen them by soaking the masks in a mixture of warm water and Elmer's (white) glue - about 1/4 cup or so for 2-3 gallons - before molding. They swear by that instead of commercial leather stiffeners. I've never tried it myself - but was planning to do so on a couple of tooled masks the kids want for next Halloween. Any leather chemists out there know if that would have detrimental long-term effects?

As an aside: Wonderful site and forums! I am coming back to leather carving after a 10+ year hiatus and this has been a wonderful resource. I can tell that many of you have forgotten more about leathercraft than I have ever known. Thank you all for your insight.

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

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

What does the Ammonia do?

My two cents...

I'll dip my piece in relatively hot water (hot enough that I can still leave my hand in it and not get scalded). I've been adding a drop of dish detergeant to my water bath since it acts as an agent to break up surface tension and allows the water to get into the leather quicker and more uniform. Depending on the type of leather you are using (and weight), you may only need to leave it in for a few seconds or it might take up to a minute. If you have the really dried out sun baked leather like the stuff called Craftsmans Grade at Tandy's, it'll take longer - better leather needs less soaking. Now mold the leather to the shape you want. At this point, this is the step that I have found to have the best effect on stiffening the leather. I place my piece in front of one of those ceramic heaters with the little fan. It seems to "temper" the leather and seems to lock in the form. I don't put it so close that it gets hot, i just set it about two feet away and let the warm air dry it out. I'll usually leave it there for 6 - 8 hours. Voila, stiffened leather. Finish as you see fit.

I have not tried drying it under the sun but, that might work too. But, if your going to dye any color other than black, you might have some issues with the UV rays darkening your leather. You're also a bit limited to working only on warm sunny days. I live near Cleveland and we don't get very many of those. ;)

Hope this helps.

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Well, I am certainly no expert at anything leather related, but I made a sheath for a knife I made and I hardened it by soaking it in a bowl of hot water from the sink (I let it run hot until it started to steam) until bubbles stopped coming out, then I did my molding. It's a pretty stiff piece of leather now :)

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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

So, what did you end up doing and how did it turn out?

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do any of the glues, detergents, or additives, act as a block out if dying after soaking? or is it preferred to dye prior to soaking?

thanks , tony

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do any of the glues, detergents, or additives, act as a block out if dying after soaking? or is it preferred to dye prior to soaking?

thanks , tony

I always mold first then use a deglazer before I dye. I've never had any issues with the detergent acting like a blocker. Realistically, I'm only using a drop in about a gallon of water. Maybe it doesn't do anything at all but I started doing it the same time that I started placing my pieces in front of the heater to dry. It works for me so I'll continue to do it. It seems to make sense to me that the detergent would help. I think what's really going on is that the water is acting as an agent to relieve the oils from the leather itself and thus creating a way for the leather fibers to bind closer together. We've all seen the Dawn Dish Detergent commercial where a drop of soap disperses the grease in an instant.

Maybe someone with a chemistry background or more knowledge on this subject could chime in and tell us exactly what the wet molding process is actually doing and if any of these additives are truly necessary.

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Thanks to everyone for the helpful tips. I'm starting to make leather masks to sell and my first test held it's shape somewhat, but not enough to make it useful. Gonna give the water and Elmer's Glue a try to see how that works. My wife is going to decorate the masks, so maybe the glue will seal the leather well enough that she can just simply paint them. Here's a pic of my first test mask:

IMG_20120603_155530.jpg

Arnold

Edited by The Leather Monkey

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I know a guy who swears that soaking the leather in urine puke.gif (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.

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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

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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

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