1. 320 to 400 grit for most applications. Higher polish with rusting times and carding material adjusted to keep higher polish in tact. A final quick polish with fine scotch brite (maroon or white) will put a nice look on the barrels and remove the grit lines from the paper.
>
2.Laurel Mountain for slow rust. No damp box used. Winter time I still just let them hang and rust naturally, though they will take about 24hr to rust. I recoat the first layer with a second with no boiling/carding to the first after about 12hr to get it going. After that, no second coating.
For hot rust blueing I use Mark Lee solution. I used to use all the older ones but they contained mecury (and worked wonderfully by the way!). Even the old formula Birchwood Casey Quick Barrel Brown was a fantastic hot rust blue because of it's mercury bichloride. It's been reformulated too. The 'new' old Herters Belgian Blue formula from Brownells suprisingly to me seems to have the merc still in it, doing a test on warm brass, so I've stayed away from that also. I shake enough already.
>
3.No rusting box
>
4. Application slow rust soln with a small pad of old T-shirt material. Just enough to wet the surface. It should be dry or starting to dry at one end of the barrel by the time you are at the other end of an application stroke. Never try to touch up a spot that is already gone over. If there is a small sliver of space that is missed, it will be coated in the next pass. To try and catch it by recoating now will result in a spot in the blue in most cases. Hot rust blueing I apply to first couple of coats with a small pad of degreased steel wool. Seems to get it to bite into the surface better and get a more even coat started. Tough on the fingers!!, it gets hot and your fingers look like a chain smoker when finished, but gloves don't make it for me when doing this. The last few coats of hot rust soln I use a small 'acid brush'.
>
5.Boiling time for slow rust is about 10 minutes. For hot rust depending on how many parts I'm juggleing at one time through the process perhaps a bit more.
>
6. Carding wheel run at approx 500rpm I think! Keep it clean! and straighten out the wires once in a while by combing a stiff wire brush through it. Light steady even pressure. Avoid 'going after' a spot and using some heavier pressure to remove the coating if it is stubborn or in a spot that is hard to reach. Even a .003/.005" wire wheel can mark up the surface through the new blueing. They don't call them 'scratch' wheels for nothing. I do use some steel wool for small spots but really do dislike the stuff. Degrease it with dishwashing soap while still in pad form first, rinse well, then unfold and lay out on the tank cover while the water heats up to dry it out.
>
7. # of coats depends on the steel. Older guns require less to get the color you may want. Newer steel don't often blue well with hot rust blueing, or sometimes with certain slow rust solutions either. Sometimes you have to experiment a bit to find one that works well. A light acid etch to the surface to start can help a problem barrel or a case hardened part (03 Sprfld action) at the expense of loosing some gloss. 4 or 5 coats of blue on most older barrels seems normal. 8+ on some of the newer stuff that says I don't like to be rust blued. Very dilute circut board etchant works good instead of acid for an preblueing etch too. Don't overdue and plug the bores for the etching part. I never plug the bore while blueing and have never had a problem.
>
8. I heat the double bbl sets back up with a torch carefully to get any water out from between the ribs. Once cooled down to just warm to the touch I coat with linseed oil. Other parts dry of their own heat and get linseed also. I've always used linseed. Just seemed to be a good thing instead of gun oil that was made to loosen and remove rust which is what I just spent so much time producing and applying. I don't always use the 'let it set for a day' thing, but I used to do that and still do on occasion. Sure doesn't seem to hurt anything. Afterrust can be a problem with some solutions. Laurel Mountain is one in my experience. It does have Ferric chloride in it I'm told so that may be why it wants to continue to rust. A room temp bath in a bakingsoda soln followed again by a rinse helps. A light carding with 0000 steel wool lubed with linseed oil a couple of days after the blueing is completed also helps and also brings up a nice gloss on the blue. I think it removes a top layer of after rust and evens out the surface nicely.
>
>
40+ years of rust blueing