My names Ben, "beng" http://www.facebook.com/bengsart long time lurker, learned a LOT form everyone here. I have been printing regularly for about 12 months not gig posters, more pop arty pieces on art paper doing editions of between 5-10. I've been using combinations of spray painted color stencils with screen prints over the top for details. I have done a few 2 color screen prints to work on my registration techniques, and this weekend I tried to do my first CMYK print.
My registration was good, I opted to not use the hinge clamps, they have developed some slack over the last year and they also sit too high from the table surface so I end up with too much snap distance at one end. I use duct tape to fix wood blocks to the table top around all corners of the screen frame, its laborious but holds really solid. I taped 3mm of cardboard spacers to all corners for the snap spacing. I made my own vacuum table which holds the page in place nicely. The screen mesh is 305t/in and the separations are printed at 65LPI. (hope I have the lingo correct)
The problem I have run into I think is with the paper I printed on, its a 300gsm Water Color Art paper with a toothed texture, the ink seems to spread out when it hits the page and I lost a lot of the definition between the very detailed little dots. So i ended up with a very dark image. I only printed YMC (not the blacks) and it was already very dark. There is also a dappled effect which I think is a result of the paper texture. The images below show the original digital image, and some of the prints. The final print in the image was the best of the 10 prints I did.
I have read that there are some pre-coats that can be done on the paper to stop the ink absorbing the paper and spreading out so much. Not sure if this is the best solution or if I should try some smoother paper with lower absorbency. Any comments or suggestions would be most appreciated. Thanks for your patience.
also, you should buy some halftone clear. part of the deal with process inks is they are transparent, so the darkeness of the colour can be affected by the paper, or the amount of ink going though the screen. A double pull on a process print is a no-no.
But once you start printing after making your stencil, with whatever mesh count and paper, you need to compare a 100% print of your colour to a sample of the correct cyan (or yellow or magenta)
If it is too dark with one pull, then add the halftone clear until you get the correct density of blue (or yellow or magenta)
Then print the print.
there is a lot to the game of printing good halftones/process. Next time you print, have some different papers available. the smoother the sheet, the better it will print.
Thanks Andymac, more awesome advice. I'll have a talk to the supplier where I get my inks and ask about the halftone clear. As for paper, I'll have to do some hunting, the choice is pretty limited in Singapore. I'll post an update after my next round of tests.