Moldy Watercolor Palettes

QUESTION:
I left my watercolors in the palette over the summer to garden. From time to time I put a damp cloth over them & sprayed them with water. Several have grown mold. I'm able to scrape off the mold. may I use them w/out trouble. How do you store watercolors in a palette for up to 2-3 months?  
Judy, Olympia, WA

Susie's Reply:
Hi Judy,  I have several suggestions for you. Let's start with the mold issue. Scraping the mold off is a good start. A solution of vinegar and water will also neutralize any mold spores that remain.
If the paint is a professional grade watercolor it should be OK.

Let's talk about storing watercolor paint in a palette. Allowing the paint to dry between painting sessions is not going to harm the paint especially if its professional grade.
Many artists prefer to paint with freshly squeezed paint straight from the tube.
Some watercolor paints are made with emollients or additives (such as honey) that aide in keeping the paint moist. Many believe that the paint must be kept moist to maintain the paint's integrity.  For many years I was included in this group of believers. And I can't tell you how much paint I washed down the drain at the end of each painting session. It wasn't until 1990 when I was fortunate to take a workshop with Zoltan Szabo that I learned dry paint was just as vibrant when reactivated as it was straight from the tube.
Some watercolor pigments and the formulas the manufacturers use are better suited for using dry than are others.
So here are my suggestions: If you feel you must use moist paint don't squeeze out more than you can use in a few days or maybe even up to a week. Use a palette with a snug lid and consider putting a moist sponge in the mixing area when the lid is on the palette.
If you will not be using the paint again in a few days, remove the lid and allow the paint to dry naturally. When you are ready to paint again add some fresh paint on top of the dried paint and replace the lid. The moisture will sink down into the dried paint. 
I hope this helps answer your questions.
SUSIE

Comment: I have 2 large palettes with paint in them....when I go to class they are too large to transport conventiently...I have since bought a smaller palette....is it okay to take the old paint out of one of the larger palettes and use it in the smaller palette? Is there an easy way to do this? Thanks Dee Cee

Yes! It is fairly easy to transfer paint from one watercolor palette to another. When the paint is dry its almost like a rubber block that will "pop" out of the well with some gentle prodding. Secure the dry paint block in the new palette well by squeezing some fresh paint of the same color into the well to act as a glue. Let it dry to cure and setup before using it.
Clean the paint block with a damp brush if there is renegade paint dried on it. Try it! Susie