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Dried out paste flux

Hi – I guess I’m a lurker here, learning all kinds of things, but
without enough knowledge to respond to anyone’s questions!

I have some fairly new paste flux – I bought it in September. I’ve
been very careful about closing the lid tightly but this paste is no
longer as runny as it had been. What can I add to this to make it a
bit more liquid again?

Thanks for any advice!
Linda in Virginia

Hello Linda,

It seems to be a fact of life that flux can dry out rather quickly.
Especially when one does not secure the lid at day’s end, as in my
own case!

It is a simple matter to ad a little distilled water, which can be
done many times over the life of the flux. Tap water can sometimes
cause problems with solder flow if high in mineral content as ours
is in Southern California. I learned this anecdotally from my
teacher Deb Jemmott and have never forgotten it!

Susan Ronan
Coronado, California

All that you need do is to add enough water to make the consistency
that you want. If you have a large container of it, you may want to
put a smaller amount of it into something like a film canister for

Marilyn Smith


When I was taking my first metals class, we used distilled water to
dilute our flux. I still use it and have had no problem. Add water
in small amounts, mixing throughly between, until desired thinness.

Happy Holidays!

When I worked for a welding supply Company we stocked the Silver
brazing flux cap-side down, and then when it was opened the new flux
was on top. Another tip: add a little alcohol to the dried flux to soften it up.