Dealing with Dead Case Foam
Posted: Sun Jun 20, 2021 1:30 pm
Between my own pistols and those owned by the college where I coach, we've got over 50 pistol cases with foam glued into them. Over time, the foam first gets a little crunchy, then it begins to disintegrate into dust, and in some instances, it also gets sticky. I suspect a lot of the exact failure mode depends on amount & type of oil that may have been used on the pistols. At some point, the foam no longer provides any cushioning for the pistol, and it also leaves dust or bits of foam stuck to the guns.
The vast majority of the cases used by European gun makers come from Negrini in Italy. Walther (& Hammerlis built by Walther), Pardini, Steyr, Morini, MatchGuns, Benelli, FAS, etc. all use Negrini cases of one sort or another. Negrini uses a very strong rubbery glue to attach the foam into the cases. Over the years, I've tried various techniques to get the old adhesive out, which usually has enough foam stuck to it that trying to just cover it with new foam doesn't work very well. I've tried scraping it off, cutting it off, solvents & heat without much success.
I finally came up with an approach that works remarkably well that I thought I would share. The next time I do this, I will try to make a video, but I'll describe it as best I can now.
The adhesive is stretchy, but if you try to just pull it off, it will snap if it is stretched more than a centimeter or two. The secret is to pinch a piece of the adhesive and pull up slowly so it begins to peel off the inside of the case. Once it's up a finger width, pinch it with the fingers of the other hand, and continue pulling up slowly. Keep switching fingers/hands in the fashion, kind of going hand over hand, but on a smaller scale. The adhesive will come up in a black sticky mess, but it will come off, leaving almost no residue on the inside of the case. One you've got a ball the size of a large marble, it's usually best to break it off and get rid of it. The adhesive prefers to stick to itself and other objects more than fingers, but not by much. You can't just "throw" it away, you need to stick it to some sacrificial surface you can pitch.
Continue pinching & pulling along the zig zag pattern of glue until it's all up on one half of the case. Flip the case over and do the other half in the same manner. I did a Benelli case last night, and it took about 15 minutes a side.
Because I have a lot of the same sized cases to deal with, I've made cardboard templates for the case foam. You can use a sharp knife like a snap-blade cutter to cut the foam, but I have a hot wire foam cutter that makes it go very quickly. The one I have is a commercial one, but there are lots of plans on-line as well.
The foam I use is grey "egg crate" foam. It comes in various stiffnesses & thicknesses. You don't want it too thick, or too stiff, or you will have difficulty closing the case, possibly even breaking the hinges. The best foam I've found for the thinner hard plastic Benelli cases is "1 pound" density, and 1 1/2" thick (nested) from this outfit:
https://www.cameronpackaging.com/egg_crate_foam.html
For the thicker polypropylene cases used by almost everyone else, you can use slightly stiffer & thicker foam. This place has 1.3 lb density foam, in 1 1/2" thickness that works well:
https://www.foambymail.com/EC/eggcrate- ... -foam.html
Caution: The way the two companies measure thickness is different! Cameron measures the thickness of two pieces nested with each other, where Foam By Mail measures one piece from the back to the peaks. As a result, 1 1/2" thick foam from Foam By Mail is thicker than 1 1/2" thick from from Cameron.
If you find that the foam is still a little thick/tight in spots, you can cut the peaks off in that area, like where it presses against a grip. I cut the foam slightly oversized so it will stay in place in the case without glue. This makes it easy to replace, and I can store thin parts, patches & manuals under the foam.
The vast majority of the cases used by European gun makers come from Negrini in Italy. Walther (& Hammerlis built by Walther), Pardini, Steyr, Morini, MatchGuns, Benelli, FAS, etc. all use Negrini cases of one sort or another. Negrini uses a very strong rubbery glue to attach the foam into the cases. Over the years, I've tried various techniques to get the old adhesive out, which usually has enough foam stuck to it that trying to just cover it with new foam doesn't work very well. I've tried scraping it off, cutting it off, solvents & heat without much success.
I finally came up with an approach that works remarkably well that I thought I would share. The next time I do this, I will try to make a video, but I'll describe it as best I can now.
The adhesive is stretchy, but if you try to just pull it off, it will snap if it is stretched more than a centimeter or two. The secret is to pinch a piece of the adhesive and pull up slowly so it begins to peel off the inside of the case. Once it's up a finger width, pinch it with the fingers of the other hand, and continue pulling up slowly. Keep switching fingers/hands in the fashion, kind of going hand over hand, but on a smaller scale. The adhesive will come up in a black sticky mess, but it will come off, leaving almost no residue on the inside of the case. One you've got a ball the size of a large marble, it's usually best to break it off and get rid of it. The adhesive prefers to stick to itself and other objects more than fingers, but not by much. You can't just "throw" it away, you need to stick it to some sacrificial surface you can pitch.
Continue pinching & pulling along the zig zag pattern of glue until it's all up on one half of the case. Flip the case over and do the other half in the same manner. I did a Benelli case last night, and it took about 15 minutes a side.
Because I have a lot of the same sized cases to deal with, I've made cardboard templates for the case foam. You can use a sharp knife like a snap-blade cutter to cut the foam, but I have a hot wire foam cutter that makes it go very quickly. The one I have is a commercial one, but there are lots of plans on-line as well.
The foam I use is grey "egg crate" foam. It comes in various stiffnesses & thicknesses. You don't want it too thick, or too stiff, or you will have difficulty closing the case, possibly even breaking the hinges. The best foam I've found for the thinner hard plastic Benelli cases is "1 pound" density, and 1 1/2" thick (nested) from this outfit:
https://www.cameronpackaging.com/egg_crate_foam.html
For the thicker polypropylene cases used by almost everyone else, you can use slightly stiffer & thicker foam. This place has 1.3 lb density foam, in 1 1/2" thickness that works well:
https://www.foambymail.com/EC/eggcrate- ... -foam.html
Caution: The way the two companies measure thickness is different! Cameron measures the thickness of two pieces nested with each other, where Foam By Mail measures one piece from the back to the peaks. As a result, 1 1/2" thick foam from Foam By Mail is thicker than 1 1/2" thick from from Cameron.
If you find that the foam is still a little thick/tight in spots, you can cut the peaks off in that area, like where it presses against a grip. I cut the foam slightly oversized so it will stay in place in the case without glue. This makes it easy to replace, and I can store thin parts, patches & manuals under the foam.