Paper Absorbency Questions

[apshaitwister]

These are most likely silly questions, but I haven't been able to find good answers yet. I'm in the middle of printing the same image on several different kinds of paper, all French, but some #65 and some #100.
It seems like the images printed on the #65 paper turned out with a lot less definition than those printed on the #100 paper, and I'm curious as to what the reasons for that might be. Does the weight of the paper have anything to do with that? Or how much ink I pull across the screen? Or how much pressure I am applying? These all seem like they'd be valid factors, but I guess I'm just really curious as to why all the prints done on the #100 paper turned out great, while almost half of the prints on the #65 turned out mediocre.
Any thoughts?

[vrooooom]

What do you mean by definition? Pictures?

[Quinine]

Sounds like you have experienced paper stretch. This is discussed in great detail on several other threads on GP. It involves a lot of factors including the amount of ink being introduced in relation to the density of the substrate as well as the environmental humidity in which you are printing. I can't speak for anyone else but I simply refuse to print multiple layers on anything less than 80 lb unless it's absolutely necessary for a particular project / reason. It's also a good idea to rack your paper for a day or two to acclimate to the environment in which it will be printed on. Search the forums and you will find a lot more on the subject. Good luck.

[Andymac]

you printing with vacuum? the heavier paper might not be lifting as much as the lighter paper. No vac = blurs sooner or later.

Also, some papers do absorb and bleed more. Interesting.

if you have vac, and all other things being equal, and one paper has a 50% reject rate compared to 100% good on the other, well....don't use the 65lb in the future, and you eliminated THAT problem. Only a few thousand more fuckups to deal with and you will be an OK screenprinter if you keep at it.

[apshaitwister]

I'm printing with vacuum, but honestly, the day of printing is was doing NOTHING to hold the paper down. Major faux pas I'm sure, but I was just letting the paper stick to the screen and then peeling it off (not sure what I could have done to get it to stay down...), doing my best not to pull it towards me and smear the ink. I would have assumed that that was accounting my problems, but I was doing the exact same thing with the higher weight papers and they were coming out just fine. I don't have pictures to upload right this minute, but I'm sure it would help you all to know exactly what the problem looks like.
By 'definition' I mean that a certain area with a lot of detail just seemed to be getting too much ink. But why would that be an issue with the #65 and not the #100? hmmm...

[SkatRadioh]

Are you flooding before you peel the print off? That'll dramatically affect the amount of ink certain areas get; it'll be completely uneven. Are you covering the holes of the vacuum table where the paper doesn't lay? The force of suction will focus on the paper and be greater, improving the effective snap of off contact you want to happen.

[apshaitwister]

I wasn't flooding before peeling the print off.
So let me get this straight...you're saying that covering the holes that aren't being used to hold my paper to the table will help concentrate the vacuum to the holes underneath my paper? I will have to try that on the next round of prints.

[SkatRadioh]

yeah, otherwise the force of suction is less because of the holes left open.

edit: I'll usually just tape down extra scrap paper/posters over holes where I'm not printing with a bit of tape and an occasional strip of painters tape where needed. It helps when I want to print large areas and heavy white, that shit sticks to my screen liek wutttttttt?????

[Andymac]

try not to tape your vac holes. A piece of paper with a couple of small tabs of tape is better, easy to clean up when you change. Stick tape down it gets permananet and hard to clean

[NeroInferno]

I've bought my vacuum table from a guy who left a tape sticked to it for years. I stil cannot cancel the "ghost" on the metal, I've tried EVERYTHING!