Plumbers Black

In former times plumbers soldered lead pipe and under ground cable jointers soldered the lead under ground cable outer sheath. To prevent solder going to non intended places they masked off areas using plumbers black as it was known. Recently I've been making a small boiler, I used Copydex and a soft lead pencil to contain/restrict the Silver Solder from going to where I didn't want it to go. I remembered plumber black and wondered if it was still available or how could I make some. John

Perhaps they just 'blacked' teh metal with a sooty blowlamp flame?

Perhaps it is something like the blacking that used to be used on old coal ranges, I think it had lamp black in some sort of wax.

Ian S C

Ian, grate polish was made with graphite rather than lamp black, which enabled it to take a silvery sheen when polished. I've no idea if it's still available - my tube of Zebrite is 40 years old - but it should make a good solder resist.

George

Stovax black grate graphite polish is still available for woodburners - see **LINK**

A small amount gets everywhere - just like marking blue

Jon

Stovax black grate graphite polish is still available for woodburners -

Yes, but I expect it is not the same as George's tube of zebrite, - now that elf'n'safety have had their way with it!

Yes, still use 'Zebo' on leaded lights. (do not tread it in the carpets :-/)

There are a few materials to help here, but by far the best way of controlling the flow of any soldering or brazing materials is to use the heat. Develop the right heat pattern for your particular joint design to ensure the right amount of alloy flows where it is needed. Keith Hale's latest book (available at http://www.cupalloys.co.uk/brazing-ancillaries/index.asp) offers advice on this and all other aspects of brazing and soldering. Might I suggest a perfect Christmas present for the Model Engineer?

You could also try jewellers rouge, if you can get it, mixed with water (and some soap or detergent for wetting). It should also work mixed with oil. The object of the exercise is to cover the surface you need not to take the solder with a powder which is not affected (dissolved or removed) by the flux.

I understand that in some trades whiting (fine chalk dust) is a useful alternative.

A topic for an article, perhaps - 'Solder Resists and how to use them'

Cheers, Tim

Tipp-ex ?