Catalyst Shelf Life

If you have to ask, your catalyst is probably expired. June 29, 2009

I was wondering what the shelf life is for S/W catalyst (V66V21) for WW Conversion Varnish. I found a bottle in my cabinet which is probably five years old and want to use it up if it's still good. The website doesn't speak of the catalyst shelf life, only pot life of catalyzed finishes.

Forum Responses
(Finishing Forum)
From contributor Z:
Five years? I would not take a chance. It very well might cost you more than you save.

From the original questioner:
That's what I was thinking too, but we need to shoot one final coat on some oak doors soon. I ran out of catalyst today (my workers should have alerted me sooner that we were low) and both of my local S/W suppliers don't have that catalyst in stock! They have the V66V26. Iím not sure what the real difference is. Does anyone know?

From contributor G:
The difference is likely to be the concentration of sulfonic acid in the catalyst.
Your aged product is probably stronger because of the five years of evaporation (or migration through the plastic) of the solvent. If you can get hold of the technical specs or a S/W paint chemist, you can find the difference in concentration between what your local suppliers have and what you need, then do the calculation to find how much extra to add or leave out. Even if you find that what they have is, say, weaker than what you need, you can apply some Kentucky windage and add just a bit more. If itís stronger, less. Many manufacturers will have a table saying how much to use of their different catalysts.

From the original questioner:
That makes sense. Maybe I'll spray a sample before we shoot the doors and see how it dries.

From the original questioner:
FYI - I did find out from the SW chemical coatings division that the shelf life of their catalysts is two years.