Here are the instructions that someone called Mike sent to me:-
1) Print your image on a "laser" printer on inkjet photopaper (or copy an inkjet version on a laser copier to glossy photo paper).
Use 600DPI if you can, otherwise 300 is acceptable. Make sure your scale is right and mirrored where necessary.
2) Clean the copper well, I use wet sand paper (1000 grit), but softscrub or ajax works. Then I wipe with "denatured alcohol" and keep my fingers off the copper.
3) Set iron to the hottest setting, line up the paper and copper, and iron until you see the toner showing through the paper(ie. you see the traces faintly through the paper), iron the edges well. You can't iron it too much.
4) Fun part now, soak the copper and paper stuck to it in warm water for 5-10 minutes, then peel it off. I use fingers to rub and tooth brush to remove the glossy stuff (the glossy part of the photo paper) from the copper, make sure you do not use sharp items like your nails unless you are careful. Make sure you have all the white stuff off (the glossy stuff from the photo paper).
5) Put the etchant in a plastic tray (or glass, if you have glass tray you can warm the etchant and it will take the copper off faster). Take a plastic fork, spoon or knife and move the board in the etchant to speed it up (I slide it left and right & lift a little).
I have found that putting the board upside down works a little better (copper falls down to the bottom). Lift it up after 5 minutes and see if it is finished. Takes 5-10 minutes. If not, slide it around some more.
6) When finished, take to the sink and rinse it well. I use acetone and wipe the toner off with a paper towel. Ajax will probably work.
Buy "denatured alcohol" and "acetone" in the paint department (denatured is what I use to wipe the board before I iron the circuit on as mentioned above)
7) I hate this part. Drill all those darn holes.
It will make boards that look professional, but it takes time.
Main thing is clean copper and a hot iron.
I have done some fine work with this method. I was surprised to see how well it works.
Cleaning the paper off is the worst part. That is the hard part for me.
Also see this post:-
https://www.electro-tech-online.com/threads/first-try-with-press-n-peel-blue-results.16187/