I don’t use a sealer, because even the recommended ones tend to dull the image.
1. Solution
2. The other option is to use a printing service (photo lab). For whatever reason, their photos don’t have this problem, and de-mask easily. The resulting appearance is inferior; the edges are more prominent. But it might be good enough for your particular application. And it has the advantage of better durability.
3. If you really insist on using “photo paper”:
- Start with matte inkjet photo paper, which tends to be a little less sticky than glossy.
- Place the transfer paper sticky-side-up to the desk (taped down at the edges)
- Around 10 times: stick a piece of cardstock to it (with gradually increasing pressure with the squeegee), then pull it off.
- Around 10 times or more: stick a piece of spare photo paper to it (starting with very light squeegee pressure, increasing to medium), then pull it off.
- Stop when it feels only slightly tacky. There’s a very fine line between “too strong to pull off” and “too weak to do its job”. It takes practice.
- Apply the transfer paper to the photo, carefully avoiding introduction of bubbles, then lightly roll it down with a rubber roller (or you can manage with fingers). Again, the use of the right amount of force takes some practice.
Even after all of that, I usually get at least a few pieces that have to be recut, either because the masking was too strong and I couldn’t get it off, or it was too weak and the piece got discolored, or often both on the same page.