paper size variance, temperature, registration
I have an upcoming 2 color job and have the following question about paper size variance due to temperature/humidity and also color registration.
I will be printing the first color Wednesday night and the second color this Friday night. The registration is very important on this one and it would be great to hear any recommendations for how to minimize variances on the paper due to temperature changes between our cold garage and inside our house.
I keep the paper indoors before printing and bring indoors afterwards (would be inside for the time between passes) but is there a better approach for this project to minimize changes in the paper between the first and second pass?
Located in Colorado, very dry, especially this time of year, will be approx. 32-40 degrees the next few days (between day and night). Garage is half insulated so it’ll be a little warmer than that but still cold. Paper is 220# Crane Lettra.
Also, while I’m here, I’m considering some kind of container made with insulation to hold my ink to that I can keep it in the garage year round. Any thoughts on this? Not sure if that would insulate enough to protect the ink.
Thanks for any assistance.
Josh
Hi Josh,
I can attest to the fact that at least humidity has a major effect on paper size, especially machine-made paper that tends to shrink and swell in one direction.
What you might do is get a couple of thermometer/hygrometers to gauge the differences in the areas where the paper will be for any length of time. Then you can do what needs to be done to equalize those differences. You also could keep the paper in a closed container to minimize at least the humidity differences.
Just some thoughts,
Barbara
Why not keep the paper out in the garage the whole time? It will shrink or swell with the temperature afterwards, but both colours will have been printed and will distort accordingly.
This is always a very tricky thing in screen printing, especially as ink coverage is usually larger and the film is thicker. Humidity makes a huge difference, and if you want to make sure nothing is going to change between passes, you need to pre-rack your paper. I know that in letterpress we don’t ever rack paper to dry, racking your blank paper in your garage prior to printing will acclimatise each sheet before printing. If your pile is not separated, the middle of it will still be used to the environment of the paper mill/warehouse and will shrink or swell once printed.
Always good to test, proof 10-20 copies and see how much this affects your register.
Perfect advise, both of you. I’ll acclimatise beginning today and will use a hygrometer to assess the difference in humidity.
Thanks so much.
Josh
I agree with modernman and keep the paper (stock) in the garage the whole time.
Josh
The advice you have been given is correct. The paper needs to acclimate in the environment in which it will be printed.
Curtis Paper Mill (now long gone) used to supply a spec sheet with its papers that indicated the packaging should be opened and the paper sit at least 24 hours in shop before processing.
The only time you would deviate from this is if you are dampening paper. In this case you are controlling the environment and the shop environment is your combatant.
Gerald
http://BielerPress.blogspot.com
Thanks, guys. The job is in progress as I did the first pass last night. The stock is in the garage waiting for the second pass tomorrow evening.
Thanks for the advice.
Josh
did you have any advice about registering the polymer plates for a 2 colour job?
Nickelyacht, it’s a pretty easy process, but it depends a bit on your guides. If your guides are more or less static (using metal gauge pins, and they have to clear a base) then it’s a little less troublesome to adjust the plate on the base for registration. If you have crop marks, you can draw alignment arrows on a base that has grids. If using polyester backed plates, you can tape them in position to your setup sheet and then “pull” an impression to attach them to the base in position.
If you have ample clearance for guides or use guides that won’t be crushed by a base (I use paper guides made from red press-board often enough) then you can also tape a transparency or sheet of tracing paper to the top sheet and pull an impression on that. Then just align the tracing paper proof to the press sheet and lock in guides. This isn’t a good idea for “crush-able” guides, since you need to keep their position in mind at all times.
James Beard
Vrooooom Press
www.vrooooom.org
thanks james, will have a bash at that.