I'm still struggling a ton here, and losing a ton of prints in a run because of it. Take last night for example. Color No. 1 was a very pale yellow. Everything printed A-OK, I had a tape guide on the bottom and right to keep the print in the same spot. Come to color No. 2, a silver metallic. I CANNOT see any of my registration points, and I don't trust where the positive was burned enough to go blind. So I sit and trace by hand all the crosshairs, and yet the silver still layed down probably 3pt. off alignment. By the time everything got right, I just blew like 7 prints out of 30.
There's got to be a better way, I know. Andys, Rich, Richie, anyone? I need tips for getting my registration better. This is starting to drive me nuts.
I got a little trick for anyone trying to 'chase the registration'
Assuming you can see the the reg marks from the previous colors you can take a small piece of clear film and tape one edge to the table so that it will hang or 'flop' over the sheet enough for you to print the new reg marks from the screen you're using onto the piece of clear film. Place a piece of scotch clear tape over the printed reg mark. That way you know exactly where the the reg marks will print assuming the screen is held tight in place.
Then lay the sheet you want to print on the table so that the previously printed reg marks line up with the reg marks printed on your 'floppy guide'
More time consuming and kind of a pain in the ass to line up each sheet but it really works nicely if you have no other choice
I forgot to add once the sheet is lined up to the floppy guide reg marks just flip the floppy guide back out of the way until the next sheet.
That way you aren't printing the reg marks on the floppy guide evry time
you have to do a couple of things to your set up to ensure you can keep register.
Start with the film. If it doesn't line up, nothing will.
Screens for critical work should be well tensioned (20 newtons or thereabouts) and all the same tension. otherwise they will stretch and deflect different amounts while printing
Clamp system needs to have no play in it. If you are using jiffy clamps on the back or side of the screen, clamp a block (or two) at the front so the screen frame can't flex when printing.
Always print in the same direction. If you use two different size squeegees on two screens (because one design is smaller) you may distort the print so they have trouble registering.
Register tabs - 3 tabs, 1/2"x3/4" or so, you can make them out of pieces of stickyback vinyl material stuck about 3 layers thick, or use some thin metal with d-tape on the back. they should be in one corner (2 tabs) and then the last tab is placed along the longest side of the paper or stock from the corner. Set this up so it is in front of you and easy to get the paper into. this is called 3 point register an is how it's done. These tabs should be the thickeness of your paper (no higher or you may rip your screen or miss your print in that area) and they must be hard enough you can rest the paper securely and positively against them.
Mark your corner and side location of your tabs on your set-up sheet and place your tabs in these same locations on all colours. doesn't hurt to mark print direction on this set-up sheet, and you will have to mark the corner and side on the top sheet if your piece is going for outside finishing (diecutting, cutting, embossing etc)
Here's where it gets tricky....when printing, place the fucking paper securely against the tabs, every time, exactly the same way. If you race through slapping the paper in, your print colours will never line up, even if you have everything else (tension, tight clamps, micrometer adjustment, perfect film, etc) covered. Especially your first colour. If that is the case, you need to make some Longtooth tabs.
Always print some crappers for set-up, and use those to start each colour run, then you won't wreck good prints adjusting register. You can line the print up by looking through the screen, with your positive taped in position on your register set-up piece. Get it perfect(no white showing between the positive and the stencil), Place your new tabs, being careful not to move your register sheet (turn your vacuum on for registering so the paper won't move). You may want to allow for some deflection (stretch) it usually goes 1/16-1/8 in the direction of the pull.
Once you start your print, check closely and adjust your tabs as necessary. Once you have established register, don't move the tabs, and always try and print with the same pressure.
One final tip....BUILD IN TRAPS AND DESIGN SO YOU CAN BE A BIT SLOPPY. It's way easier than trying to trap some sliver of white on either side of a print.
Some things that will screw up register:
Not registering with 3 small guide tabs - if theyare too big (or a piece of tape) you will not have a positive and precise interface between the tab and the paper.
Not letting your paper acclimatize - once the first colour is down, and the paper dries, it will resize to your shop humidity. Rack it over night.
if you have a dryer, run your paper first, before printing.
Changing register corners or side location during the print or colour to colour
Too much lift = distortion
Ink getting too thick, pull too hard = distortion
Ink dries in on first colours, points close in, don't register to later colours
two differnt people hand printing (uneven squeegee pressure)
Screens loose or not clamped, too much flex
Table or register devices not locked.
Adhesive on tab guides on to fresh, pop off or move over run.