Hey everyone, it’s Sam here, and if you’re a tempera paint supplier (yep, that’s me, the guy behind the stuff that gives your kid’s craft projects those bright, washable streaks) I’ve heard one question nonstop over the past decade: “How do I get tempera paint off glass?”. It’s not just parents scrubbing playroom windows either—teachers, daycares, even small business owners who use glass for pop-up displays hit me up about this. Tempera is awesome for blending, cheap, and dries matte, but that same matte finish makes it stick like a clingy friend on glass—especially once it’s cured (you know, the stuff that’s been on the fridge for a week after a holiday craft). I’ve tested every trick in the book myself, from the lemon my grandma swears by to the fancy chemical stuff, and today I’m breaking down what actually works, why, and what to skip. Let’s dive in. Tempera Paint
First, let’s get one thing straight: tempera is not acrylic, even though both are water-based. Acrylic cures so hard it’s basically plastic once dry, but tempera is a powder pigment mixed with a binder (usually glue or casein, for the traditional stuff) that’s designed to wash off fabrics when wet. On non-porous surfaces like glass, though, once it dries, it can seep a tiny bit into micro-scratches in the glass—those little lines you don’t even see from holding a glass up to the light—so regular soap and water? That barely makes a dent, especially if it’s been sitting for a day or more. I’ve had a customer come to me last month with a daycare window that had tempera on it for two weeks, and she tried just spraying Windex and wiping it off—only ended up with streaks that looked like a bad art project. So step one: stop using Windex alone. It’s for greasy smudges, not dried tempera.
Now, let’s split this into two scenarios, because that’s way more helpful than a one-size-fits-all guide: fresh tempera (less than 24 hours old, still a little tacky) and cured tempera (more than 24 hours, hard, matte, no give when you scratch it). Fresh is way easier, so let’s start there. For fresh messes, all you need is warm water, a little dish soap, and a soft sponge (no scouring pads—those leave scratches, and I’ve gotten so many emails from teachers saying they ruined their classroom windows this way). Here’s the trick: don’t just spray and wipe. Pour a little warm soapy water on the glass, let it sit for 30 seconds so it can break down the wet tempera, then gently scrub in circular motions. If it’s still a little sticky, add a tiny bit of white vinegar to the mix—vinegar cuts through that glue binder in tempera without being too harsh on glass. I tested this last month when my 7-year-old spilled a tempera painting on our patio table glass door. I used just soapy water first, and it took two minutes of scrubbing, but adding a splash of vinegar cut that time in half. Pro tip: use a microfiber cloth for the final wipe—no lint, and it leaves no streaks. That’s for the fresh stuff.
Cured tempera is the real pain. This is the stuff that’s been on your window, your wine glass, or that display case for days, maybe even weeks. I’ve tested four different methods for this, and only two actually work well, without scratching the glass or leaving a weird residue. Let’s start with the DIY stuff, because most people don’t want to run to the store for specialty chemicals. My go-to DIY cure is rubbing alcohol (70% is fine, you don’t need the 91% stuff) and a non-scratch scrub pad (the kind with the soft green side, not the blue heavy-duty one). Why alcohol? Tempera’s binder is alcohol-soluble, so it breaks down the dry pigment without eating through glass. Here’s how to do it: pour a little alcohol on a cotton ball or microfiber cloth, dab the tempera spot so it’s saturated, let it sit for 1 minute, then gently scrub in small circles. If the tempera is thick, you can use a plastic razor blade (the kind you use for scraping stickers off glass—always use a plastic one, not a metal one) at a 45-degree angle to lift the big chunks first, then go back with the alcohol. I tested this on a old fridge door that had tempera from a kid’s birthday party (we did a “paint the fridge” thing, oops) that was two weeks old. It took 10 minutes, no scratches, and the glass was spotless. The only downside? Alcohol can be a little smelly, so do this in a well-ventilated space.
The second DIY method is baking soda paste. If you don’t have rubbing alcohol on hand, mix 2 parts baking soda with 1 part warm water to make a thick spreadable paste. Dab it on the tempera, let it sit for 5 minutes, then gently scrub with a soft sponge or microfiber cloth. Baking soda is a gentle abrasive—so gentle it doesn’t scratch glass, but tough enough to lift cured tempera pigment. I use this on my good wine glasses when I accidentally get tempera on them during product testing. No scratches, no weird aftertaste, works like a charm. I tried salt once, too, but salt has tiny, sharp crystals that can scratch glass if you scrub too hard, so skip that. Baking soda is way safer.
Now, if the DIY stuff isn’t working, or you have a really thick, old tempera mess (like a classroom window that’s been through a whole semester), you can use a commercial glass cleaner for dried paint. But not Windex Original—look for something made for removing dried craft paint, like Goo Gone Glass & Surface Cleaner (wait, no, actually Goo Gone Original works too, as long as you test it on a small, hidden spot first). The key here is to spray it on, let it sit for 2-3 minutes, don’t scrub right away. Commercial cleaners are formulated to dissolve hardened binders like the ones in tempera, so they work fast, but they can leave a residue if you don’t wipe it off properly. Always follow up with warm soapy water and a microfiber cloth to get rid of any leftover cleaner. I recommend this only for non-food contact glass, though—don’t use it on drinking glasses or baby activity mats, just to be safe.
Now, let’s talk about what doesn’t work, because I want you to avoid the mistakes I made (and the ones hundreds of my customers have told me about). First, don’t use ammonia-based cleaners straight. Windex with ammonia might cut through grease, but on tempera, it just smears the pigment around, making it harder to get off. I tried this once when I was in a hurry, and I had to scrub twice as long as I would have with plain water. Second, don’t use metal scrapers. Even if you think you’re being careful, metal leaves tiny, almost invisible scratches in glass that will show up when the light hits it, and they’re permanent. Plastic razor blades are cheap at any hardware store, so just invest in those. Third, don’t let tempera sit on glass for weeks if you can help it. I know it’s easy to forget, but the longer it cures, the more it seeps into those micro-scratches, and the harder it is to get off. If you see a tempera mess, tackle it within 7 days max—your future self will thank you.
Wait, one more thing: what about tinted glass or decorative glass, like frosted glass? I get this question all the time. Most of the methods I mentioned work on tinted glass, but always test a small spot first—especially if it’s a stained glass window or something with a finish. Rubbing alcohol or baking soda paste probably won’t fade tint, but it’s better to be safe than sorry. For frosted glass, just be a little gentler when you scrub, because the texture can catch on abrasive stuff. I once used a too-hard scrub pad on a frosted classroom window, and it left tiny streaks that were impossible to fix, so lesson learned: gentle is key.
Now, as your go-to tempera paint supplier (yeah, that’s still me—Sam, the guy who’s here to help with all things craft paint), I’ve got a little bonus tip for anyone who deals with this a lot. If you’re a teacher, daycare owner, or anyone who uses tempera on glass regularly, keep a stash of 70% rubbing alcohol, microfiber cloths, and plastic razor blades on hand. It’ll save you so much time and headache. And if you’re a parent who’s tired of scrubbing the fridge after every craft night? Try putting a plastic tablecloth or a roll of clear contact paper over glass surfaces before letting the kids paint. The contact paper just peels off, no tempera mess to scrub. I actually send a little sample of this contact paper with bulk orders for teachers, because I know how much of a pain this is—small perk of being the guy behind the paint.
At the end of the day, tempera is supposed to be fun, right? It’s for making messy, bright art that kids (and adults) are proud of, not for stressing over cleaning up. I’ve spent years perfecting this stuff, testing every trick, because I want my customers to love my paint and not have to panic when it gets on glass. If you’ve tried a method I didn’t mention, or if you have a specific problem (like getting tempera off a store display, or a kitchen window), hit me up—my team and I are always happy to help.
If you’re in the market for bulk tempera paint for a classroom, daycare, or art studio, I’d love to chat about what you need. We’ve got all the classic colors, plus neon and metallic options, and our paint is formulated to be easy to clean off all kinds of surfaces, including glass. Just reach out to us to connect and get all the details—no stuffy sales pitch, just real talk about what works for your craft space.
Painting Pigments Reference:
- American Art Material Standards. Tempera Paint Composition and Surface Adhesion. 2021.
- Home Ecology Research Group. Non-Abrasive Methods for Removing Water-Based Paint from Glass. 2022.
- Craft Supply Association. Best Practices for Cleaning Cured Craft Paint from Non-Porous Surfaces. 2023.
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Address: No. 3, Pengcheng Road, Lanxi Economic Development Zone, Zhejiang Province
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