Foam Sticking to Kydex

L

Lance Carrico

Joined
Jan 4, 2013
Messages
28
Last night I tried my first hand at making a kydex sheath. The problem I encountered was that, when I removed the kydex from the press, the foam stuck to the kydex and tore the foam. The kydex molded well and was useable, but now the foam is damaged and I had to scrape the foam off the kydex. The press and foam are from Knife Kits. Do I need to spray a release agent? What did I do wrong?
 
Foam normally sticks a little bit but should pop right off. There's no need for release agent. What temp are you heating the kydex to? What are you using to press the foam and kydex?
 
heating to 325 degrees. A little concerned that perhaps the direct heat from the elements is making it hotter. I set the cast iron press on the floor and stood on it. I'm thinking I need to place a barrier between the heating elements and the kydex like aluminum foil or something. It is a convection toaster oven.
 
Couple of questions
1. how are you getting your temp reading?
2. I hope I miss read this, but did I read that you're placing the kydex directly on the heating elements?
3. How thick is your kydex?
PS Please fill out your profile...
 
My first thought is that 325 is much too high. You should be able to mold easily at just over 200F up to 250F. You could try a bit of WD40 as a releasing agent sprayed lightly to the foam before pressing.

--nathan
 
I always heat my kydex to about 275, 300 max. A bit of stickiness with the foam is the norm but if you're getting damage then I assume like the others that 325 is too high. Also, standing on top of the press is probably quite a bit more pressure than necessary and could be adding to the problem.

I've found what works really well is to line up the hot kydex and knife on the press, lower down the top and clamp it to the work bench with a fair amount of force using an Irwin pistol grip style clamp, but then I release the clamp and let it pop up, easing off the pressure before locking it again. What this does is give a really good initial shaping of the kydex to the blade but when you relax it just enough so the knife isn't too tight in the sheath when it cools and also gives the foam just a bit of breathing room.

I'll post a couple pics in a bit of how mine is setup.....
 
You may be overheating it.
Pam works, but it's just canola oil thinned with alcohol
Just give a quick wipe with canola oil

I think heavy pressure is good for forming- but it will vary if you tape it or not and so on.



If you add 200 pounds weight on a 12"x12" press, that's only 1.4 PSI
 
12345678910 said:
If you add 200 pounds weight on a 12"x12" press, that's only 1.4 PSI
Click to expand...

That's good to know, I'm 211 and used to stand on my press, which was about 12x12... I've always wondered what the optimal pressure was for forming. Not something they've published, or that I recall seeing in their spec sheets...

Anyways, I asked how you're measuring the temps because if you're using an oven gauge, you're not getting an accurate reading... you need to take the temp of the material. Also you have to remember that if you set the temp to say 300 degrees the oven will go over that, then stop when its temp gauge reaches 300, then it will cool and the heating elements kick on again and that cycle repeats until the ambient temp is a constant 300. When you open the door, you lose heat and the cycle starts again...

Most people just use a paper towel under their material and that's good. Personally I don't use any thing to buffer... It's best to use a cookie sheet and not lay your material directly on the heating elements (duh) or the wire rack...

My last question is paramount above all the rest... the thickness and the type of material you're using dictates the optimal molding temp. A lot can be learned from reading the data sheets

If you're using Kydex, the brand
http://www.kydex.com/technical-data/product-data-sheets.aspx
 
I always have the foam separated from the hot Kydex by a piece of material like a pillow case or old bed sheet, no sticking problems and less melted foam. I would say your temp is too hot also.
 
Thanks for all the great responses. I do not place the kydex on the heating elements. It's a toaster oven that has exposed elements, and I think the radiant heat was overheating the kydex. Couldn't sleep this morning, so I was out in the shop a little after 4am playing with it. What I did was to place a double layer of thick aluminum foil on the top wire rack to shield the kydex from the radiant heat. I placed a thickness of stainless foil on the bottom wire rack, which is over a pan, further shielding it from the rising heat and keeping the kydex from "drooping" down through the racks. The oven is convection, so the heat circulates well. I sprayed the foam lightly with Pam, which solved my sticking problem.

First couple of tries were at 300 degrees for 5 minutes, which proved to be too low. Perhaps I wasn't letting the kydex soak long enough. I seemed to get the best results from a pre-heated 350 degree oven for 5 minutes. All worked great then. I am suspecting that my oven temperature is WAY off. I will put an accurate thermometer in and verify.

You guys are a great help. Thanks.
 
Lance Carrico said:
Thanks for all the great responses. I do not place the kydex on the heating elements. It's a toaster oven that has exposed elements, and I think the radiant heat was overheating the kydex. Couldn't sleep this morning, so I was out in the shop a little after 4am playing with it. What I did was to place a double layer of thick aluminum foil on the top wire rack to shield the kydex from the radiant heat. I placed a thickness of stainless foil on the bottom wire rack, which is over a pan, further shielding it from the rising heat and keeping the kydex from "drooping" down through the racks. The oven is convection, so the heat circulates well. I sprayed the foam lightly with Pam, which solved my sticking problem.

First couple of tries were at 300 degrees for 5 minutes, which proved to be too low. Perhaps I wasn't letting the kydex soak long enough. I seemed to get the best results from a pre-heated 350 degree oven for 5 minutes. All worked great then. I am suspecting that my oven temperature is WAY off. I will put an accurate thermometer in and verify.

You guys are a great help. Thanks.
Click to expand...

Yea you're way over heating your material, and aren't measuring the temps correctly... I've never had an issue with my material (Kydex or Boltaron) sticking to the foam.

Anyways you should come hang out in the Sheaths and Such section, many good threads on this stuff there.
 
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