I’ve seen a couple of folks using White Out(tm) to line the interior of cans for canister damascus.
That is not necessary; there’s a cheaper solution and this is it:
Here’s the scoop. White Out is collodion (nitrocellulose dissolved in ether and alcohol) with titanium dioxide white pigment in it. It totally makes sense what is going on: the titanium dioxide coating will not weld and acts as a “resist” on the inside of the can. I recognize the smell of collodion immediately because I used to use collodion in wet plate ambrotype process photography. So, that got me thinking about making my own paint with titanium white in it – and then I remembered KILZ and Zinnser cover-up white paint: that has to have a bunch of titanium dioxide in it – so there’s already a product out there that is exactly right for the job.
Today I tested that, by spraying the interior of a canister I was making with a spritz of KILZ. Then I packed it with motorcycle chain and 1095 powder, welded it, pressed it, and used a diamond wheel to cut the welded ends of the canister off. After that, I did a horizontal cut, slid a chisel in, and the whole canister just pried right off the billet inside.
As you can see, there is no sign whatever of the billet welding to the canister.
Have Fun Forging!