I only painted with gouache briefly and will be interested to see the answer of others. I have 2 stay wet palettes from painting with acrylics. I found they made the paint too wet. I think you might lose the creamy texture that is so nice about gouache.

Gurney has several blog posts with videos about using gouache.

http://gurneyjourney.blogspot.com/search/label/Gouache

I believe that he keeps them moist for a limited time on a wet paper towel.

I use a wet paper towel in my stay wet palette to paint with caseins. I do not try to keep them active over a long time. They can not be re-wet.

Maybe someone else has had a better experience.

I tried to use stay wet palette and didn’t like it because I just didn’t want to keep a full palette of paint wet for long periods of time. At the time I was going back and forth between transparent watercolor and gouache. That got to be a pain, so I settled on a china plate for a gouache palette for short periods of time. If I need to keep colors wet for awhile, like over night, I put a wet paper towel on the plate then cover it with cling wrap.
I think you are going to have to find what ever you are comfortable with by trial and error.
Good luck and enjoy your Gouache painting.
Regards,
Greg

I use the Masterson’s small Sta-Wet and love it. It keeps the paint moist for at least a few days…enough for me to finish a painting. Quite a luxury to be able to not have to continuously scrub dry clumps of paint to get the color you need. Highly recommended.

Ah forgive my poor etiquette and late reply- thank you all! I ended up getting a large rectangular slab of porcelain tile from the local hardware store (Home Depot) it was under $2. I found that before I place gouache on, if I put it in the fridge beforehand, it keeps it cold and gives a longer working time ☺️ I feel like I wasted a lot of gouache in the process of figuring all this out 🙁

I’ve used the small sta-wet for qouache and it works very well. I’ve also used it for Casein and although it doesn’t stay for weeks, it works fine for a few days. I just give it a spritz of water before I close it up. I’m now trying it with acrylic gouache (or should we say flat acrylic paint) and I’m finding that it picks up quite a bit of water from the paper and the underlying sponge layer so I’ve been careful to keep it flat between uses or the paints can tend to want to run together. That goes for the casein especially if you add casein medium to get the paint to some creamy consistency.