Preventol: how to use?

[Matt Leahy]

Hello,
I just received a package from Kremer containing a small bottle of Preventol. I'd planned to add it to an ochre which had previously developed a very dark and healthy mold. I dumped it and planned to add the Preventol to a new dispersion. I also was going to add a little to some other mold-prone pigments and maybe gesso.

For some reason, I was expecting it to be liquid but it is more of a salt-like crystalline substance. So, I'm not sure how much to add or even how to add it. Should I grind it in along with the dispersion, and if so, how much? Perhaps I shouldn't even use it?

Thanks!

[Dennis H]

You may want to phone the folks at Kremer and ask them. I've found them to be pretty helpful in the past.
Dennis

[Alessandra Kelley]

I'm curious too. And has anybody noticed if Yellow Ochres are especially prone to mold? I've had it happen several times.

[JeffG]

Iv'e only had it happen to raw umber water/pigment paste in a jar.

[Bert Congdon]

I have had mold grow on several pigments that were ground in water. I added the Preventol and gall to my distilled water.The gall helps with the dispersion of the pigments, a little like a wetting agent, and the mold no longer grows. I love these ingredients, and I swear by them.

[Matt Leahy]

How do you add it and how much? Should I reduce it to a powder and mix it into an already dispersed mixture, or grind it with the pigment during the dispersion process? I'll give Kremer a call, but I'd also love to hear about your process.

Thanks for the help!

[Bert Congdon]

It easily disolves in water, so I see no need for grinding it finer. How much? I believe Kremer says not over 1%. I put about a rounded tablespoon in a gallon of water. Again, I disolve about the same amount in an 8oz bottle of water. I use this stronger solution when I add water to those pigments that already have mold.

[Matt Leahy]

Thanks again for the information. I hadn't had time to check to see how hard the stuff was. I appreciate it!