3 Easy Ways to Prevent a Moldy Gouache Palette (and what to do if it happens)

How to prevent moldy gouache palette

It seems that this topic has popped up quite a bit more in my YouTube comments lately, so I thought I’d address it in detail. I genuinely wonder how many people struggle with this issue? Maybe I should do some kind of public poll.

In This Post

What is mold?

It’s a fungi, but not a fun guy.

I recently heard a Ted Talk about how amazing fungi is. And I also learned it’s literally everywhere. At all times there are fungi spores on almost every surface on earth. Some environments promote faster growth, while others don’t allow it to grow at all.

When you close the palette and it seals tightly, it creates a moist environment for those spores to reproduce. Contrary to what you might believe, fungi is not trying to ruin your life. It’s just doing it’s thing. The only thing it can do, really.

Spores can travel via air, water, and stick to almost any surface, including your paint.

Mold can be fuzzy, slimy, or look like discolored dots on your gouache. Sometimes it’s milky white and other times it’s brown or black.

What to do if you already have mold in your gouache palette?

  • Remove and discard the moldy gouache and thoroughly clean the palette out.
  • Disinfect your palette, either with distilled white vinegar (straight out of the bottle) or rubbing alcohol. Do this in a sink, and use gloves to avoid getting the solution on your hands.
  • If your palette is metal, let it soak in boiling water. (Note: many plastics will melt in boiling water, try that at your own risk)
  • Disinfect your brushes by scrubbing with dish soap and warm water (not boiling! that could melt synthetic hairs).
  • I regularly use Master’s Brush Cleaner & Conditioner to clean my brushes

3 Ways to Avoid a Moldy Gouache Palette

Now let’s talk about how to avoid mold in the first place.

1. Add Clove Bud Oil to your Gouache

Clove bud oil is a strongly scented natural oil with anti fungal properties.

Clove oil is from the same plant, but not as strong as clove bud oil.

How to use Clove Bud Oil to prevent mold in your gouache palette

The rule of thumb is to use as little as you need to get the job done.

  • First mix a diluted solution – fill a 50ml plastic spray bottle with water, add 10 drops of clove but oil. Shake vigorously.
  • Spritz gently into your clean palette.
  • Add your gouache to your palette.
  • Give a quick spritz of the solution to the top of your gouache.
  • Stir each color individually with a toothpick (clean toothpick after each color so your don’t mix your colors)
  • Don’t go overboard and spray too much, as too much oil can change how the paint behaves.

If you have FREQUENT problems with mold, especially in specific colors, try this:

  • Add one whole drop of clove bud oil to each color that has issues.
  • I know I said don’t use too much oil, but I found that one or two drops doesn’t really change the consistency too much, plus I dilute my gouache with water when I use it.

2. Open and Use the Gouache Palette Frequently (at least once a week, if not every few days)

This is my preferred method. By opening the palette and using the gouache, not only does this help prevent mold but it also means you are USING it and hopefully IMPROVING your skills!

So how does this help prevent mold growth? It’s some crazy science thing that says disturbed paint doesn’t give spores enough time to reproduce.

If you don’t have time to paint every few days, put a note on your calendar to stir the gouache. Simply open, stir each color individually with a toothpick, and close. I’ve kept my palette mold-free for years by doing this.

3. Use Distilled Water when Painting

I personally have not needed to try this, but I’ve had many comments on my videos saying this helps. It certainly can’t hurt!

Bonus Tip

Mold likes warm, moist environments. So remove any extra water in your palette before you close it. Try soaking up excess water gently from on top of each color with a paper towel before closing. You can also let it sit opened for 5-10 minutes before closing. And if you still have problems, keep your palette in the refrigerator between uses. I don’t recommend freezing it, because it might cause the palette to crack.

Do Some Brands of Gouache get More Moldy Than Others?

I’m in the process of finding out! I am doing a ‘mold test’ on all of the gouache brands in my gouache database.

It’s on the shelf growing as we speak. I’ll be updating the gouache database page regularly in the coming months.

The Takeaway

Mold likes moist, dark and warm environments. Deny it of these conditions and you’re on the right track to avoiding mold growth in your gouache palette.

Some cleaning or additives can be useful, but most importantly, USE THE GOUACHE frequently!

Watch my video about this topic:

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I'm an independent artist living in Scotland. Always chasing the light, and painting the beautiful highlands.

4 thoughts on “3 Easy Ways to Prevent a Moldy Gouache Palette (and what to do if it happens)

  1. Sarah, do you ever use wet mixing palettes like those from RedGrassgames, Army Painter, etc.? These aren’t marketed per se for gouache, but I have heard some success stories, (especially regarding Redgrassgames) from Holbein Acryla gouache lovers who’ve begun their journey with traditional gouache. Sounds like this has potential as a useful/versatile gateway palette. Cheers and thank you for sharing your passion, dedication, and research!

    1. Yes, I use the Redgrass V2 for gouache often. I’ve been using it for a couple years now. It’s in my ‘fave supply list’ and appears in many of my studio videos.

  2. Hi, Sarah! I am a huge fan of all your work, from your artworks to your scientific research, to your teaching. I see you recommend clove bud oil to keep gouache from getting mouldy. Do you have any information about whether tea tree oil would work instead? I haven’t been able to find anything on line saying yes or no to that. Thank you for all you do!

  3. Thanks Sarah for the sharing your mould tips. The only time I’ve had that happen was when I left paint in my sta-wet palette over the Christmas break so it was closed up for about 3 weeks. Most of the time I’m opening it a couple times a week, using paint that’s left and adding more. I cleaned and sanitized the whole thing and started over with fresh paint. As I think you said before, the only wasted paint is the paint that doesn’t get used and that’s likely when it might get some mould. Fresh paint and fresh palette mixing space is refreshing. I use artist quality brands, similar to you as well. I haven’t yet tried my plein air leakproof palettes like the ones you use. Looking forward to that when weather warms up a bit.

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