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Screen printing signs... cobwebs?

Flame

New Member
Hey guys, been printing some coro signs... and for some reason I keep getting "cobwebs" on my prints. use 220 mesh, straight plastisol ink, 60 degrees out...

what am I doing wrong? lol.
 

Baz

New Member
It's the combination of a fine screen mesh with thick ink. Try thining some down and see if that helps. I personaly use 200 mesh screens with multi purpose ink. No cobwebs.
 

Flame

New Member
o phooey on the homemade press. lol. It gets replaced tomorrow anyways.

Betchya that's my problem, never thinned the ink, off to try it. Got over 300 signs to crank out in 2 days, gotta figure this out! :)
 

G-Artist

New Member
We never get that until winter. Then it is a horror. You need humidity to reduce static
or some static string. We are going to be looking at an air ionizer anti-static rig sometime soon as they are made one county down from us.

All our print tables are metal covered and grounded. We use all-metal screen frames and they are grounded as well. Thick / thin ink is of no consequence in our operation. Your drying racks should grounded as well. It is a static problem, pure and simple.
 

Dave Drane

New Member
If you are wiping the Coro as you print them it can make static too. definately thin the ink and use a little extra "lift off" with a vacum base or double sided tape on the table.
 

Farmboy

New Member
A little off topic...how are you curing these? We print with a coro ink from nazdar. I tried running one off these through my dyer just for the hell off it. Warped the crap outta it.
 
Welcome to the world of Coro. The peoblem is usually low humidity which causes static. The cure is usually take a dryer sheet and wipe the sheet as it is put in the press, the funny thing is you only have to wipe one side even when printing both sides, there is a reason for this. Never tried plastisol on coro, how do you get them dry? Plastisol needs heat and the heat and the amount of heat required will melt the coro or at least warp them. Use Nazdar 7900 and retarder, wipe with dryer fabric sheet and print baby print. Need help call me will be glad to help anyway I can.
 

Gino

Premium Subscriber
In our years of working with screen inks, paints and clears...... it has always been a combination of conditions. When the frost is on the pumpkin, you must mix your liquids for a particular kind of inkie dunkin', but when the weather's hot and sticky.... that's the time for regular inkie dunkin'.

You have to be aware of your surroundings and realize that there is no exact science for most any of this stuff, unless you have a year-round temperature controlled facility. You're always going to be mixing a little heavy or light, thinning or retarding your inks and paints.

Usually, the spiderwebbing comes from the ink being too thick and drying before the air can do it naturally. It's probably drying in the screen for you, also. Thin it down by 10% and if that doesn't do it..... box it out and go in 5% increments until you have your desired consistency. Mark all of your finding and either write it all down or store it away in your computer under screen printing tips. These things will eventually be ingrained into your brain and you won't have to second guess yourself anymore.

What you're building up is experience and when something isn't used very often, we many times forget and get caught wasting time and money. Lucky for many of us here, we have :signs101: to come to for our help.
 

SignManiac

New Member
The culprit is more than likely static. Very simply, static electricity occurs whenever two materials are mechanically worked together, or when two materials in contact are separated rapidly. Through a process called tribo-electrification, electrical equilibrium is disrupted. One material loses electrons to become positively charged while the other gains them to become negatively charged. The material's conductivity determines its ability to pass along this charge. Good conductors, such as metals, can lose a static charge almost immediately. Insulators, such as plastics, retain their static charge - sometimes for weeks.

Many normal handling operations generate static. These include parts moving on conveyor belts, sliding down chutes, or simply rubbing against each other. In fact, manual cleaning with tack rags or using a compressed air blow-off to remove visible dirt will impart an invisible static charge to attract and hold more dirt as the part travels through the production pipeline.

I even had serious issues with our UV flatbed. The winter is the worst time.
 

d fleming

New Member
At the risk of being called a nasty name from the poster again I will throw in my 2 cents after 30 years of screenprinting. Plastisol on coro is the wrong ink for the application. If you use multipurpose (9700 from Nazdar) you will need a catalyst, if you use corogloss (7900 same vendor) you will not. The webbing (if you were using the right ink) is from your ink drying in the screen, you need some retarder. With plastisol your webbing is most likely something else becuase plastisol has to be heat cured but it doesn't matter because it's the wrong ink for coro anyway. 220 mesh is fine. When you are ready to get away from your homemade press (started with one myself) I have a very nice awt clamshell for sale. Do not use too much retarder or you will wait next to forever for your prints to dry, instructions come with it. Try not to have too much ink in screen while running your prints. Nazdar has the inks and additives you need and they are the best in the business.
 
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