Let's use our good friend Bowser here to demonstrate:

Make your bead art normally

Make your bead art as you normally do. Since we will be using tape to remove the beads off the board the final work will be flipped horizontally or "mirrored" so keep that in mind.

Use masking tape to cover the beads

Masking tape or painters tape work well. If the tape is curly and you’re hesitant you can wreck the beads so go gentle but boldly. Press tape down on entire piece with finger, popsicle stick, anything you want just make sure all beads are stuck to the tape.

Gently take the beads off the board and set it on your ironing surface tape down beads up.

Iron only until beads begin to fuse

Add your parchment paper and start ironing. Try to use new parchment paper (buy a roll from a grocery store) since the paper Perler provides has creases and they can transfer to the final piece - fresh is best and will ensure smoothness.

For ironing I use a medium-high heat on the iron and keep it moving constantly. I rotate the artwork every 20 seconds so it's heated evenly.

Lift the iron every so often to see the progress of the melted beads (through the paper). You want a partial melt where the beads are fused and start to get square shaped but don't go for the full flat melt yet.

Remove the tape carefully!

Flip the art over, carefully remove the tape, then flip it back and resume ironing and go for the full flat melt. The beads should stick to the parchment paper a bit.

Iron more and occasionally look at the beads through the paper (don't remove the paper it can create streaks) to see the progress of the melt.

After ironing I put a heavy book on top of it so it stays flat as it cools. The total cooling should only take 5-10 minutes.

All done!

After the final piece has cooled and you remove the paper If you find there are still small holes you can put heat/parchment paper back on and iron more just don't remove the parchment paper mid-iron with warm beads because it can create streaks.

If you iron too long you may run into the issue of colors bleeding into each other so find the balance you are comfortable with.