Liquid tin solidified

[matthuszagh]

A few months ago I used MGChemicals liquid tin (https://www.mgchemicals.com/products/electronics-prototyping/electroless-plating/421a-liquid-tin/) to tin plate the edge connectors of several extender cards. I then left this in the pyrex container, stored it in a dark place and then pulled it out again today to do the same. But, it had solidified (image attached). The consistency is a bit like a gel.

Is there a way to prevent this so that I can reuse the liquid tin, or do I have to discard it each time after use? During the tinning process it was exposed to sunlight. But I stored it in a dark place.

[james_s]

Did  you seal it in an airtight container when you stored it? If you don't do that, some of the components will evaporate.

[matthuszagh]

Did  you seal it in an airtight container when you stored it? If you don't do that, some of the components will evaporate.

That probably explains it. No it's one of those pyrex containers with a rubber top. I doubt those are air-tight. That's good to know.

[Nusa]

Add water (deionized preferred) until you have close to the volume you had when you stored it. Give it a few minutes to soak in, then mix best you can by swishing or using a safe-material tool. See if it works.

[Ian.M]

That Pyrex dish has a large surface area, and even with a close-fitting lid, I'd bet it lost a lot of water due to evaporation.

Try re-dissolving the residue in a *small* volume of deionised water.  Gentle heating in a waterbath may help.   If it dissolves, check if its still active by applying a drop to a freshly prepared bright copper surface.   If so, I'd bet it will keep much better in a small tightly stoppered jar.

If not, it will be desirable to minimize the bath volume, by making a narrow shallow enclosure only slightly longer than the edge connector, as its quite likely that you'll find that used plating solution doesn't store well even in a sealed container.

[T3sl4co1l]

Yeah, dissolve it in water, can't hurt to try I suppose.  Beware, it may have oxidized, so have lower activity than before.

Probably best is to just, you can wipe that stuff on, right?  Just soak some paper towel and go, no need for immersion?

Tim

[Gary350z]

The technical datasheet says "Volume lost due to evaporation can be replaced with DI water".