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Stopping the flow of solder

Every so often someone asks what to use to stop solder from flowing when making a new join. We seem to, as a group, resist using yellow ochre, and there is good reason for that. I actually like it, as long as I don’t immerse my ochred piece in my pickle after soldering. Ochre is an iron-based ore, and will contaminate pickle.

Then peeps suggest Wite-Out, which is fine to use as long as you use the water-soluble product and not the one that’s made with solvents. The solvents are the problem, as they create truly nasty fumes that can damage the only pair of lungs you’ll ever have.

Ronda Coryell has made a product, Masking Mud, which I love. It’s much easier to clean up after use than White-Out or Ochre, produces no nasty fumes, and, yes, it does what it’s supposed to do, stops solder flow when you don’t want solder to flow. I am not affiliated with Ronda and/or any supplier of the product (just sayin’ in the interest of full disclosure).

I have used yellow ochre as that’s what I was taught to use in instructional environments but also have used white out. They both work.

Would scalex also work?

Maybe I’ll go try.

It’s just clay, correct?

Yes, Scalex works, I used it the other day when I couldn’t find the whiteout. Basically you can use anything to “dirty” the metal where you don’t want the solder to flow. Just scrub it off with soap & water before pickling.

I use whiting, which is powdered chalk. Doesn’t contaminate pickle, washes out easily, and is cheap (any chemical supply store). Just make sure you don’t mistake it for your borax powder :wink: !

Janet in Jerusalem

I read you can use milk of magnesia, has anyone tried it?

It’s basically calcium and magnesium, so I’d say you’re good to go, even though I haven’t tried it myself :slight_smile:

graphite from a pencil works as well

I always use polishers Rouge. Just file off some powder and soak with a bit of alcohol.