Everything you have read about ironing a creased canvas applies to a blank one. Once the canvas is painted, the rules change completely, because dried acrylic softens when it is warmed. Press a warm iron near it and the paint film can gloss, deform or stick to whatever is against it, and that damage is permanent in a way a crease is not.
So the order of operations here is: weight first, mounting second, heat almost never.
Method 1: flatten under weight
Slow, safe, and effective on most shipping creases.
- Lay the canvas face up on a flat surface.
- Cover it with clean, plain paper. Not newspaper, which can transfer ink, and not anything textured, which can emboss the paint.
- Put a flat board on top, then books or another even weight across the whole surface rather than in one spot.
- Leave it. A few days for a mild crease, two weeks for a stubborn one.
Make sure the paint is fully cured first, which means a week or so rather than dry to the touch. Acrylic stays slightly soft for a surprisingly long time, and pressing paper onto a not-quite-cured surface is how you end up with paper fibers embedded in the sky.
Method 2: mount it to a board
This is the permanent fix and the one worth doing on anything you care about.
Cut foam board or thin plywood to size. Attach the canvas with acid-free double-sided tape or spray adhesive, working from the center outward and smoothing as you go so the crease is pulled flat rather than trapped. The result is rigid, so the crease cannot come back, and it drops straight into a standard frame.
Framing under glass with a mat achieves something similar and also covers the trimmed edge on an unframed canvas. Take it to the frame shop flat, not rolled. There is more in how to frame a paint by number canvas.
Method 3: slight damp, from the back only
For a crease that weight alone will not shift, and only if you are prepared for a small risk.
Lay the canvas face down on a clean towel. Wipe the back of the crease with a barely damp cloth, damp enough to darken the fabric and no more. Turn it face up on clean paper and put it straight under weight until it is completely dry, at least twenty-four hours.
What you are doing is relaxing the fibers from behind without letting moisture reach the paint. Do not spray, do not soak, and do not do this to a canvas that is not fully cured.
What not to do
- Do not iron a painted canvas, from either side and at any setting. An earlier version of this page recommended a high setting, which was wrong. Heat softens the acrylic film. Ironing from the back still conducts heat through a thin canvas.
- Do not use a steamer. Heat and moisture together, which is both problems at once.
- Do not spray fabric conditioner on it. It leaves a residue on the paint surface that varnish will not sit on properly afterward.
- Do not leave it in the sun. Sunlight fades acrylic, and a few afternoons in a hot window will do more visible harm than the crease.
- Do not try to stretch it over bars if the canvas is trimmed close to the printed edge, as unframed kits usually are. There is not enough margin, and pulling distorts the image.
If the paint has cracked along the crease
Sometimes a fold made after painting cracks the paint film, leaving a hairline of white canvas showing. Flattening will not fill that.
The repair is straightforward if you kept the pots. Once the canvas is flat and dry, run the matching color along the line with the finest brush, in one pass rather than dabbing. Let it dry, then look at it in daylight from a few feet away. Most repairs disappear at that distance. If a color has run out, there is a matching extra paint set for every design.
Avoiding it next time
- Deal with shipping creases before you paint, not after. A blank canvas can take gentle low heat from the back with a cloth barrier; a painted one cannot. There is a full method in how to flatten a paint by number canvas.
- Never fold a canvas. If you have to move a finished piece, roll it face out around a wide tube, which puts the paint film in tension rather than compression and stops it cracking.
- Buy framed. A framed kit arrives already stretched on a wooden frame, so there is nothing to crease and nothing to mount when you finish. You can see those in framed paint by numbers.
- Check how a kit ships. Ledgebay canvases ship rolled in a tube rather than folded, which is why most of our customers never meet this problem.
Other customers' finished and framed canvases are in the customer gallery, and the full range of designs is in the catalog.
