Kirk Hays wrote:
<snippety snip>

> >
> > This process is (was?) used by gun-smiths when fitting
> > an action to a stock. They called it "smoking a fit"
> >
> > Perhaps someone more knowledgeable than I can confirm?
>
> It's a classic technique, still in use by better gunsmiths
> and by home gunsmiths, like myself.  Works well for fitting
> any metal to wood surface - used it to mount my Emmert to
> the bench.
>
> Smoke from a carbide lamp is the best, as it is nearly pure
> soot.  Calcium carbide is getting tough to find, inexpensively.
> Chemical supplies want $50 for a pound, USP, which is too much
> to have around (it gives off acetylene over time, a potentially
> explosive gas with a flashpoint around room temperature), too
> expensive, and of unnecessary purity.  You used to be able to get
> "welding grade" calcium carbide from welding shops, but I haven't
> found one lately that stocks it.
>
> Alternate marking methods include lipstick, but try explaining
> to SWMBO just why you've got her lipstick...or, worse yet, why
> there's lipstick on your shop clothes!

My father used to do this using "Prussian Blue". As near as I can tell
this is just artist's oil paint which dries very slowly. Basically you
put a thin coat of PB on the metal surface and carefully fit the metal
to the wood without any sliding around.

I've used it myself from time to time, but it can be kind of messy - at
least in my hands.
One should be careful not to get the paint on parts that will show.

It might be a little safer than having open flames in a wood shop.

I've also used a pencil to put a coat of graphite/pencil lead on one
surface that leaves marks on the surface you're fitting too. I used to
do this when fitting dovetails when my technique was a little more shaky
than it is now.

Carl