how would i iron paper onto hdpe?
It works on the fiberglass of PCB's pretty well, much better than the copper side. If you try it on HDPE I'd like to hear how it works. I don;t have any HDPE sheets but I do have some standard polypropylene sheets which are pretty smooth. I'll be making some PCB's this weekend so I might just test it out myself.
anyway... Print your image, mirrored, onto some paper. I've gotten away with using regular old 20lb copier paper but the non-recycled type with some cyclamen clay in it like color printer paper would be better (the 24lb stuff should do). You could also try a transparancy. ymmv.
Next, clean the board well and remove any fingerprints. maybe even rough it up a tad with a scrubber sponge.
Then, cut out the image and lay it on the board. It's much easier if your artwork is smaller than the surface you plan to transfer it to.
Heat up a clothes iron to the highest setting, no steam, and press. hard. for about 7 to 10 minutes. After the first minute or so, the toner will pretty much hold the paper to the board. I like to run back and forth and switch sides to evenly heat and to make sure the holes in the bottom of the iron dont leave "cold" spots on the board. Alwyas strive to keep the iron in contact with the board and level.
After you're done heating and pressing, drop the board into some cold water and gently peel the paper away. If you use cheap paper you'll get a lot of "hairs" left behind with the toner. After the toner cools you can really rub on it with your thumbs and very little toner seems to come off. I also like to do this while the board is submerged. I've found that using a scrap of the peeled paper as a scrubber helps me too. It's a labor of love haha
x-acto knives are a lifesaver when doing this. If you mess it up...just clean the toner off with some alcohol and a scrubber sponge and try again. Been using this method for PCB traces and occasionally the screenprinting side for a long time.