Hardening leather: the finer points (not remaking the wheel)

[Andeerz]

Ok... necroing this thread because I think my questions belongs here:

I wish to use a heat gun to harden my leather via the water and glue method as my oven is complete crap and has wild variations in temperature that end up making my pieces unevenly hardened with areas of scorching. Anyone have experience using a heat gun in this way? What do I need to be aware of? Any suggestions on proper technique? Would a variable setting heat gun set at 200 degrees Fahrenheit do the job well? Anyone completely opposed to the idea? If so, any suggestions for alternatives? Does simply immersing a leather piece in 175 degree water or water/glue solution work well?

[Russ Mitchell]

I've done it. It works just fine so long as you don't burn the piece. I haven't done "hot immersion," b/c I like my fingers better than that.

[Andeerz]

Thanks Russ! I am assuming you used an industrial heat gun set at ~200 degrees F, no?

[Russ Mitchell]

I had mine on high, actually, but I was very careful. OH. Works MUCH better if you tack it to a form, when working this way.
I'd produce half-tanned cuirboilli like this on a regular basis (since I can handle the tanning), if I could get a decent set of forms. But I'm total shite when it comes to woodworking.

[Andeerz]

Yeah. That is my next project right now: making some decent forms. I wonder if I could make one out of plaster or hydrocal and have some small screw anchors put in so I can somehow clamp or pin the leather in place if that makes sense...

[Kilkenny]

Chris Dodson made his arm harness using a heat gun, so it can definitely be done. How difficult it is to get temps right, heat evenly/adequately across the entire piece, etc., I can't say. My personal experience trying it involved singed leather, which proves only that I did it wrong

[Kel Rekuta]

I've done it. It works just fine so long as you don't burn the piece. I haven't done "hot immersion," b/c I like my fingers better than that.

Canning tongs from the dollar store will sort that out for you. Wide grip area, specifically designed to use in hot water.

I prefer to dip the whole piece, wooden last and all for a couple seconds. Not so practical with things like leg castings though.

[Kel Rekuta]

Chris Dodson made his arm harness using a heat gun, so it can definitely be done. How difficult it is to get temps right, heat evenly/adequately across the entire piece, etc., I can't say. My personal experience trying it involved singed leather, which proves only that I did it wrong

I've used the heat gun too but one has to be very attentive. My mind wandered while repitching my favourite drinking jack recently. It still holds liquid but looks like hell. If I recall Dodson made an archer's sallet with two layers of leather over a rounded post. (RA Journal 1997) He used a heat gun and kept wetting the project while moving a lot of leather, patiently and tediously.

[Kel Rekuta]

Yeah. That is my next project right now: making some decent forms. I wonder if I could make one out of plaster or hydrocal and have some small screw anchors put in so I can somehow clamp or pin the leather in place if that makes sense...

Its easier to leave a selvage edge around the piece, and lace through that around the (well waxed) casting. Once cured, unlace and the job pops right off.

[Russ Mitchell]

Andeerz, if you come up with a relatively simple/affordable form setup, please let me know. Dobson nailed his pieces to wood, but plaster and selvedge edges seem like they'd work pretty well, too.

[Kilkenny]

Yeah. That is my next project right now: making some decent forms. I wonder if I could make one out of plaster or hydrocal and have some small screw anchors put in so I can somehow clamp or pin the leather in place if that makes sense...

Its easier to leave a selvage edge around the piece, and lace through that around the (well waxed) casting. Once cured, unlace and the job pops right off.

oh duh!.. lacing...

I'm an idiot...

yeah.. tie it onto the form, don't nail it onto the form...

of course...

Thanks for opening my eyes to one of the most obvious solutions I have ever overlooked, Kel

[Andeerz]

Oooo! Fantastic idea!

[Andeerz]

So, I have recently tried using a heat gun to harden some 10 oz. veg tanned leather I had lying around in preparation for trying stuff on the half-tanned leather I have.

My attempts were somewhat successful, but not quite to my liking and I'm wondering if I could get some input.

Basically, I completely soaked the piece with water and used my heat gun (set at what it says is around 500 degrees F) at a good distance and with tight, rapid oscillations (fast enough not to scorch the piece, which I got down pretty well) heated the stuff until I could feel the other side of the leather be just too hot to touch (which should be easily in excess of 140 degrees at least). The leather would appear to sort of lighten and change in color at this point to a color different (maybe a but more yellow brownish tan?) than the original color of the piece.

I did this all over the piece and I thought I had done it pretty evenly. After it cooled off, the piece seemed to be significantly more rigid, but some parts were still rather flexible (perhaps as flexible as before treatment). Also, it appeared to me like there was still water in the piece as after it cooled off, it was a little cooler than a piece of similar thickness that was not treated or soaked at all.

I was wondering if the inconsistency of the hardness is unavoidable given the heterogeneity of the low quality leather, or if I did something wrong, or if I can re-soak it (at least in the soft areas) and re-heat. Any advice is appreciated!

[Russ Mitchell]

In answer to your question: yes. Hide glue with the heat-gun is how I did it. Also, I found that it really didn't work quite as well if the leather wasn't under tension so much (lacing/nailing to form). For PURE water-hardening, I would recommend soaking it a bit, and baking in the over rather than heat-gunning, which seems to work much better with water/glue on a form.

[leekellerking]

I have been wanting to experiment with the techniques described in this thread viewtopic.php?f=1&t=29104&hilit=+hot+rabbit+glue+

The results were beautiful!

download/file.php?id=31300



download/file.php?id=31301



I also really like this reconstruction of a 14th Century vambrace by Chris Dobson:

http://www.masterarmourer.com/vambrace.html



Assuming that the elbow is properly covered, this would be awesome for SCA heavy combat.

Leif

[Andeerz]

Yeah... Chris Dobson's recreation of that vambrace is exactly what I want to go for eventually. I think that using a heat gun will work well, especially when I make a last.

What I find odd about Chris Dobson's manner of construction of the vambrace is that the piece already had the iron splints in while heating on the last. I would have expected things to scorch. Then again, perhaps he was patient and made darned sure to keep things below scorching temperature and just above hardening temperature (like, say, around 180 to 200 degrees).

The effect of stretching makes some sense. I imagine that during the heating process (and this is PURE speculation), the collagen fibers denature, curling in on themselves. Stretching would oppose the shortening of the fibers and perhaps encourage the fibers to hook together in a more rigid, taut structure than without stretching. That, and/or stretching allows for more even distribution of hot water in between the collagen fibers, allowing for the heat to do its thing more consistently. Keep in mind, the tannin coating the collagen is hydrophobic and helps keep water AWAY from the collagen fibers... stretching might increase space between fibers and prevent water-proof, insulated pockets from forming that don't get properly heated. And, with this, I think one of the reasons half-tanned leather works better is that there might be less crap (tannin) keeping water out of places to be hardened. I have no idea why half-tanned is much less brittle, though...

I am probably wrong about all of this, but maybe these might explain why my heating failed to get uniformity in hardness... plus the parts that were rock hard were the places that were previously stretched the most while forming.

Also, the fact that I didn't use glue definitely mucked things up, too! And seeing as how the process Joe Skeesick used involved saturation of the leather with glue while hardening... it's probably important. However, I wonder if adding too much glue might actually make the leather easier to cut (sort of like wax does).

Oh, and leaving the thing on the last for a week to fully dry and cure probably does wonders, too, which I DIDN'T do with my piece.

[Russ Mitchell]

I'll tell you flat out -- the piece I own from Dobson's workshop (via Joe, who's a personal friend), is the hardest piece of leather armor I've ever handled, period. I just utterly suck at last-making!

[Andeerz]

Nice! I can't wait to finish making a last and attempting to make something akin to Dobson's work!

Now... I would like some input on the shape of the last for the vambrace... should it be pretty much a circle in cross-section throughout with the nice tulip-shape length-wise, or should it be pretty much like a wooden version of my forearm in shape?

[Russ Mitchell]

That depends: do you want the vambrace to hug your arm and rotate with your wrist, or to hug your arm but not have to move when your wrist rotates? Round for the latter.

[Andeerz]

Whichever is period!

I hope it's the round one... since I want to just ask someone with a lathe to make me the last...

EDIT: I dunno about the lathe idea... I think it will have to be a little oblong in cross-section anyway...

[Oddbjorn_Mjolksiglandi]

Necroing my own thread.

So in last adventures of oddbjorn the stubborn newbie armorer we left our hero with some nice baked and acrylic wax sealed armor. in the following time i have learned the following important pieces of information.

soaking your (thick) leather lames in floor wax makes them stupid solid. I'm routinely asked if i used wood. It also makes any 90 degree edges painful. i recommend the time intensive process of rounding off all of your corners and edges especially before putting the armour together as unlacing/relacing lamellar is a pain.
there is a nifty drill bit used to take the sharp edges of of holes in sheet metal. invest in one and use it on your lacing holes and lacing becomes much easier.

If you are going to seal larger items like greaves of bazubands which may not get a perfect bake in the oven... well don't. seal with a meltable wax because if they soften, the outside is still sealed and will not allow water penetration for resealing.
on that note.
My "bazuband style" legs inspired by torvaldr's shinbaulds just got down checked because they lost their rigid nature. legs don't fit nicely in an oven hence my previous comment.
Does anyone have experience rehardening leather that has been sealed in acrylic wax. A local knight is going to help me make a plastic knee cop to stick in it but i'd like to eventually reharden it on its own.
Ideally, and with the success of my lames. i would buy a ballon or two of wax, put it in a bucket and stick the knee portion of the leg in it for a while.
Had anyone had this issue in the past?
Odd who learns by mistakes.