Rehydration of dried out paste solder

This is my first post. I just joined Orchid. I did a search last
night to see if anyone had figured out how to revive dried out
silver paste solder. I saw discussion about how it does dry out, and
someone found some that does not dry out. Mine does dry out, but it
seems to me that if I were to replace whatever liquid evaporated out
of it, then it should be as good as new.

We have been using both silver and gold paste solder for years. I
have not had much trouble with the little syringes of gold solder.
But for silver I prefer to use a 1 ounce plastic jar of the stuff,
and apply it to the joint with a wood toothpick. I am using Okai
Corp. silver paste solder that we get from Rio Grande. We used to
add water to thin it out, and that sort of worked. A few months ago
I tried ethyl alcohol, and that works better. But of course it dries
out fast if the cap is not on real tight. It’s obvious to me that
it’s not alcohol that the manufacturer uses. Whatever they use seems
more oily, but it’s obviously not oil. I guess I mean it’s more
viscous than alcohol.

I’m a pack rat. I hate to see anything go to waste. The alcohol
works OK, but there must be something more like what was originally
in there.

Any ideas?

Paul J. Badali
Badali Jewelry Specialties, inc.

Hello Paul,

To rehydrate our paste silver solder use mineral oil, don’t use
water or flux or anything else for that matter just straight mineral
oil will do the trick.


Thackeray Taylor
Rio Grande Technical Sales & Support
505-839-3000 ex 13903


I am the manufacturer of the paste you’re using. If you email me off
list, I would be happy to send you some of the original thinning
agent that we use to reconstitute the paste. If you prefer, you can
also use small amounts of mineral spirits to reconstitute the paste
in the short term, however, while mineral spirits will thin the paste
for use now, they will also dry out very quickly.

A quick note about solder pastes: there are a lot of different
formulations for solder pastes. The products you are currently
purchasing through Rio Grande are designed to be ‘restrictive’
solder pastes. That means that the solder paste will not spread out
as you heat it, and will tend to keep the solder alloy right where it
is placed on the assembly. This solder paste can also be used to
solder on vertical surfaces, where the solder paste won’t drip. An
added benefit of the restrictive solder paste is that it can help
hold small pieces in place during soldering. Restrictive pastes do
tend to dry out over time, because the ingredients that make it
restrictive tend to evaporate more quickly.

We also produce nondrying pastes which are not restrictive. These
pastes are a better choice if you desire a long shelf life, or if
you prefer a paste that will tend to spread out during the early
stages of heating.

Send me an email off list and I’d be happy to send you some thinner
for the paste you currently have, or a sample of a nondrying paste if
that is your preference.

Best Regards,
Michael McCoy
Okai Corporation

Manufactures of Brazing and Soldering Products for Gold, Silver,
Platinum, Palladium and nonprecious metals in Paste, Powder, Sheet,
Strip, Wire, Chopped and Sphere forms.


Try mineral spirits or paint thinner. I suppose Ronson lighter fluid
might work too. I’ve used those on gold paste but not the silver.

I don’t know what they use in paste solder, so I can’t tell you that.
The reasonably safe substance that would have solubility similar to
ethyl alcohol but more viscosity and less evaporation would be
ethylene glycol - anti freeze. Just a thought, so try a small amount
if you try. I’ve never looked for it in this way, but the less
additives, the better, of course.

Hi Paul,

I did a search last night to see if anyone had figured out how to
revive dried out silver paste solder. 

I’ve had success using mineral spirits from the hardware or paint

I use paste solder that’s sold in syringes. It tends to dry out
after a while & is difficult if not impossible to extrude from the
syringe. It dries out inspite of keeping the tip of the syringe
capped when not in use.

When the paste gets hard to extrude, I remove the plunger in the
syringe & add a few drops of mineral spirits, mixing them in the
remaining paste with a popsicle stick or other long narrow tool.

Sometimes the trick is getting the plunger out. I’ve found that
removing the needle or cap from the syringe & inserting a stiff
blunt ended wire until it contacts the rubber piston on the end of
the plunger & then removing it, breaks the vacuum that forms when
the plunger is removed. If you use a pointed wire, it’s much easier
to poke a hole in the rubber piston.

With past in a jar, you wouldn’t have to remove the plunger, so
adding a few drops of mineral spirits & mixing would be much easier.
I’d add the mineral spirits a few drops at a time mixing thoroughly
until the right consistency is reached.

Since I’ve found the paste solder that Beth Katz makes
( I haven’t had to add mineral spirits. Her
paste solder is GREAT!

Usual disclaimers, just a happy customer.


1 Like

I can appreciate that people want to use up the last bit of a
product, as anything having to do with jewelry is expensive. BUT,
using a product such as kerosene to make paste solder viable again,
one very important thing has been omitted; it is the flammability of
the kerosene. I urge anyone who is using kerosene mixed with paste
solder back to a state where it will work, PLEASE be very careful in
putting a flame to the solder paste after you have added the
kerosene. It is very flammable once this combination has been mixed.
We all work with very flammable and combustible materials, but this
one seems to be extra combustible. Please proceed with a whole lot of

Beth Katz
unique Solutions, Inc.