How to Seal a Diamond Painting (and Whether You Need To)

To seal a diamond painting, flatten the finished canvas, press every drill firmly into the adhesive, then apply thin coats of a sealer: a brush-on sealer made for diamond painting, or a clear spray. Sealing locks the drills in place and keeps dust from settling between them. It's optional if the painting is going behind glass, and worth doing for anything that will hang uncovered or get handled.

Do you need to seal a diamond painting?

Not always. The adhesive on a diamond painting canvas holds drills well for a long time, and a painting framed under glass is protected from dust and knocks without any sealer.

Sealing earns its place when:

• The painting will hang without glass. Most people skip glass because it hides the sparkle, and an open canvas collects dust between the drills.
• It's going on stretcher bars or foam board, where the canvas flexes a little and drills can work loose. Paint With Diamonds calls sealing highly recommended for pieces that will hang or go on stretcher bars.
• It will be handled, as a coaster, notebook cover, or card.
• Drills are already popping off, usually because the adhesive dried out in places or the canvas spent a long time rolled up.

If the painting is going straight into a frame behind glass, you can skip sealing and go to framing.

Brush-on vs spray sealer

There are two kinds of sealer, and they trade sparkle for hold.

Brush-on sealers are painted over the finished canvas. They flow into the gaps between drills, which is what locks the drills in, and they're water-resistant once cured. Mod Podge Diamond Top Coat Sealer is a water-based gloss sealer made for diamond painting and applied with a foam brush. The tradeoff: sealer settles over the facets, so a heavy coat can soften the shine, and a sealed canvas shouldn't be rolled afterward.

Spray sealers go on as a fine mist of clear acrylic. They keep more of the sparkle and the canvas can still be rolled for storage, but they don't fill the gaps between drills, so they hold loose drills less well. Spray outdoors or in a well-ventilated room.

Which to use: brush-on for anything that will hang open or be handled, spray when you want maximum sparkle on a piece that's already firmly stuck. Choose a gloss finish over matte (matte flattens the facets), and avoid glitter or "sparkle" formulas, which compete with the drills. One blogger's side-by-side test of brush-on sealers on The Crafty Blog Stalker is a useful look at how different formulas finish.

How to seal a diamond painting, step by step

1. Flatten the canvas. Kits arrive rolled, and the curl fights you. Lay the finished painting face down under heavy books for a day or two, or roll it gently the opposite way. Don't iron it: Diamond Art Club advises never ironing once drills are placed.
2. Press the drills. Roll a brayer or a rolling pin firmly over the whole front, a section at a time, so every drill is seated in the adhesive. A few drills that look straight are often sitting slightly proud.
3. Clean and check. Brush off dust, pet hair, and lint with a soft dry brush. Replace missing drills and straighten crooked ones now; sealer locks in whatever is there.
4. Apply a thin coat. For brush-on, load a foam brush lightly and work in one direction across the canvas, keeping the coat thin enough that it doesn't pool in the corners between drills. For spray, hold the can 8–12 inches away and apply two or three light coats rather than one heavy one.
5. Let it cure. Leave the painting flat and undisturbed. Mod Podge Diamond Top Coat is dry to the touch in about 15–20 minutes, but as the Mod Podge Rocks review puts it, dry and cured aren't the same thing. Follow the label's cure time before framing or handling.

Seal before you mount or frame the painting, not after; it's much easier to coat a flat canvas than one already wrapped around a board.

Sealing mistakes to avoid

Coats that are too thick. The most common problem. Thick sealer pools between drills, dries cloudy or white, and traps bubbles. Two thin coats beat one heavy one.

Sealing over dust. Sealer glues lint and pet hair permanently to the surface. Clean the canvas right before you start.

Steam, heat, or humidity. Ironing with steam, sealing in a humid room, or drying in direct sun can warp the canvas or cloud the finish.

Wet glue as a sealer. Ordinary white glue applied heavily soaks the canvas and can warp it. Use a sealer made for the job.

Sealing before the drills are seated. A drill sitting slightly crooked when you seal stays crooked. Press first.

After sealing

Once the sealer has cured, the painting is ready to frame, mount, or hang. How to frame a diamond painting covers sizes, glass or no glass, and mounting on stretcher bars or foam board. Sealed paintings also make good coasters, notebook covers, and cards, since the sealer stops drills from catching.

Further reading

• Paint With Diamonds: How to seal your diamond painting — brush-on vs spray, with photos
• Mod Podge Rocks: Diamond Top Coat — a hands-on review of the diamond painting sealer
• Diamond Art Club: Getting wrinkles out of a canvas — flattening before you seal
• The Crafty Blog Stalker: Best sealant for diamond art — several brush-on sealers compared