Andrew (great name, by the way!),
150 grit seems way too coarse to me, and in my limited experimenting, acetone alone doesn't seem to do an adequate job of degreasing. Try scrubbing the board using a clean scotchbrite pad with dish soap and water. When you rinse it, see if you get a clean sheeting action from the water; if not, you may still have some grease. I do use acetone as the final step. Avoid touching the surface of the board once it is clean.
A couple of other thoughts ... is the toner cartridge new, or near the end? I've heard that this can make a significant difference ... though I have to confess that I have gotten very good results with my HP 2015dn even when the "change toner soon" warning light is lit.
Finally, I have heard or read somewhere that some copper board just doesn't work well with TT no matter how well you prep it. I don't know if that is true, but if you have access to a different batch of board, you might give that a try.
Good luck -- (another) Andy
--- In Homebrew_PCBs@yahoogroups.com, "andrewmv@..." <andrewmv@...> wrote:
>
> I've just started attempting my first PCBs with the toner transfer method, and I'm consistently getting terrible results.
>
> Some sections of the pattern transfer flawlessly to the board, while others stay on the paper. I've tried varying heat, pressure, and ironing time, but my results are always similar.
>
> It never seems to be the same parts of the pattern that come though, but I never get the whole thing.
>
> My current process is:
>
> 1) Print the patterns in black toner on medium-gloss photo paper with a Dell 5310n laser printer at my office.
> 2) Scour the board blank in two orthogonal directions with 150 grit sandpaper
> 3) Clean the board blank with pure acetone
> 4) Preheat the board to about 150 degrees Fahrenheit with an electric clothes iron. I'm measuring with a handheld infrared HVAC thermometer.
> 5) With the iron at about 400 degrees, I place the pattern toner-side down on the board, and apply pressure with the iron. The pattern almost immediately fuses to the copper, as I've seen suggested it should, and I move the iron around the pattern regularly, applying a least two full minutes of heat and pressure to every part of the board.
> 6) I immediately place the board and paper into a bowl of hot water, and let it soak for 10-20 minutes.
>
> I've tried variations on this...I initially skipped the scouring, cleaning, or preheating the board. I've tried using mild pressure all the way up to my full body weight. None of these significantly improved or worsened results.
>
> I tried letting the board fully cool before placing it into COLD water, as I've seen suggested, and found that there was virtually no toner transfer whatsoever.
>
> Any tips or ideas?
>