Short answer: yes, you should know how to seal paint by numbers if you want your finished canvas to look good for years, not just for the first week on the wall. A coat of varnish protects the acrylic paint from dust, fingerprints and yellowing, and it is the difference between a canvas that looks fresh in five years and one that has gone dull and grubby. The only real decision is gloss vs matte (or the middle ground, satin), and how to apply it without ruining hours of work with a rushed second coat.
We have shipped over 1,300 custom kits and thousands more standard ones, so this is less theory and more "here is what actually goes wrong and how to avoid it." If you are still working through the canvas itself, our complete beginner's guide and our piece on how long a kit actually takes are worth a read before you get to this stage.
Do you actually need to seal a paint by numbers painting?
No, sealing is not compulsory. If you are framing the piece behind glass, the glass already protects it. But if it will hang unframed, sit on a shelf, or live somewhere with any airflow or sunlight, sealing keeps the acrylic paint from picking up dust, fading, and cracking over time. It also gives the surface a slight protective layer against light knocks and finger marks, which matters a lot if the painting is a keepsake you want to still look good in ten years.
How long should you wait before sealing?
Wait until the painting is fully, properly dry, not just dry to the touch. Acrylic paint feels dry within an hour but keeps curing underneath for much longer, especially in thicker sections. Golden Artist Colors, one of the most respected acrylic paint manufacturers, recommends waiting at least a few days for thin, even layers like the ones on a paint by numbers canvas, and up to a week or two if any area has thicker paint. Rushing this step is the single most common reason a varnish job goes wrong, because trapped moisture underneath a sealed surface can cause cloudiness or a milky finish that will not go away.
Our rule of thumb for a standard 40x50cm kit: finish painting, leave it flat somewhere out of direct sun for at least 3-4 days, then varnish. If you have gone heavy with the paint in any section, give it a full week. This is also, honestly, the part of the process that rewards patience over speed, a bit like the point we make in our post on painting mindfully: the slow bit is doing its job.
Gloss, matte or satin: which finish should you choose?
There is no wrong answer here, it comes down to how you want the finished piece to look and where it will live.
| Finish | Look | Best for | Watch out for |
|---|---|---|---|
| Gloss | Shiny, deepens colour saturation, makes detail pop | Bold, colourful subjects (florals, portraits, landscapes with strong contrast) | Shows glare under bright light or direct sun; shows brush strokes and dust more |
| Matte | Flat, no shine, softer overall look | Rooms with lots of natural light, or subjects you want to look understated | Can slightly mute colour vibrancy compared with the unsealed painting |
| Satin | A gentle sheen, between the two | Anyone who cannot decide, or wants a natural "finished painting" feel | Fewer brands stock it than gloss or matte, so shop around |
If in doubt, gloss is the most popular choice for paint by numbers specifically, because the pre-printed sections already have flat, distinct blocks of colour, and gloss is what makes them read as a "real" painting rather than a colouring page. Matte suits softer, more muted designs (autumn scenes, black and white portraits, night skies) where you do not want extra shine competing with the mood. If you are choosing your next kit with the finish in mind, our easy and intermediate collections both have plenty of bold, high-contrast designs that suit a gloss finish especially well.
How to seal paint by numbers, step by step
- Confirm it is fully dry. See the timing above. Do not skip this.
- Dust the surface. Use a soft, dry brush or a lint-free cloth to remove any loose dust or fibres. Anything left on the canvas gets sealed in permanently.
- Work somewhere ventilated. Outdoors or a garage with the door open is ideal for spray varnish. Lay the canvas flat, never upright.
- Shake the can properly. A full minute if it is spray varnish. Under-shaking is the most common cause of a patchy, uneven coat.
- Spray in light, even passes. Hold the can 25-30cm away and keep it moving the whole time. One heavy pass creates drips and a hazy "bloom" where the varnish sits too thick. Two or three thin coats beat one thick one, every time.
- Let each coat dry fully before the next. Usually 15-20 minutes for spray varnish, longer for brush-on. Check the product instructions.
- Leave the finished piece flat for at least 24 hours before hanging, framing or moving it, so the final coat cures properly.
Brush-on varnish (including craft options like Mod Podge) works too, and is a fine budget option, but it is easier to leave visible brush marks, especially in gloss. If you go this route, use a wide, soft, flat brush and work in one direction only, edge to edge, rather than scrubbing back and forth.
The mistakes we see most often
- Sealing before it is properly dry. Covered above, but worth repeating because it is by far the most common issue.
- Spraying too close. Under 20cm and you risk drips, pooling, and a cloudy "frosted" patch that will not fix itself once dry.
- One thick coat instead of several thin ones. Thick coats trap air and dry unevenly.
- Spraying indoors with no airflow. Aside from the fumes, varnish needs air movement to cure evenly.
- Touching the surface too soon. Fingerprints in half-cured varnish are almost impossible to fully buff out.
Do Paint A Moment kits come with varnish?
"Can I varnish my finished painting, and do you sell varnish?" is one of the questions we field most often through our contact form, so it is worth answering plainly here rather than making people ask. Our kits include a pre-printed canvas, numbered acrylic paints and three brushes as standard, and gloss varnish is available on request if you would like to seal your finished piece with the same product we use. That is true whether it is one of our standard kits or a custom paint by numbers kit made from your own photo. If you would rather pick your own, any of the gloss, matte or satin options above will work fine on our canvases; there is nothing unusual about the material that requires a specific brand.
What if you would rather not seal it at all?
Completely fine. Framing behind glass or acrylic glazing protects the painting just as well without any varnish step, and it is the lower-risk option if you are nervous about spray technique. Many of our customers frame straight off the canvas, particularly for gifts and custom portrait kits they want ready to hang quickly (our gift ideas guide covers more on that). Sealing is worth doing mainly for pieces that will hang unframed, or that you want to protect for the long haul, an anniversary portrait or a pet memorial piece you plan to keep for decades, for instance. Browsing for your next project? Our best-selling kits are a good place to start.
Quick answers
Do you have to varnish a paint by numbers?
No. Varnishing is optional and mainly useful for unframed pieces, since it protects the acrylic paint from dust, fading and finger marks over time.
How long should a paint by numbers dry before sealing?
At least 3-4 days for a standard kit with thin, even paint layers, and up to a week or two if any section has thick paint. Rushing this causes a cloudy or milky finish.
Is gloss or matte better for paint by numbers?
Gloss is the more popular choice because it deepens colour and makes the pre-printed sections read as a real painting. Matte suits softer, more muted subjects where you want less shine.
Can I use Mod Podge to seal a paint by numbers?
Yes, brush-on options like Mod Podge work as a budget-friendly sealer, though they are more prone to visible brush marks than spray varnish, especially in gloss.
Written by Marcus, founder of Paint A Moment. We started out hand-painting pet portraits on Etsy under the name MegaPaws, and have since made and shipped thousands of custom paint by numbers kits. This guide comes from the questions we actually get asked, not a manual we read once.
