Author Topic: Screen prep problem  (Read 1524 times)

Offline Jhtitan

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Screen prep problem
« on: April 18, 2019, 04:30:16 PM »
So we are just starting out so this was my 3rd set of prepped screens. What would cause this? the emulsion seems to have ran and dripped. This was the top of 3 screens and all under this were ruined as well.

I read someone here say 1/1, which I am guessing is 1 pass on outside then one on the inside, I have been doing 1/1/1, three pass, start and finish on the inside. Worked great on the first 12 screens. these last 4 I did I had 1 good screen and then this screen and the 2 under it all looked like this. I am using only plastisol ink at the moment, we got close to 400 gallons with the equipment so we are not planning on using anything else just yet.

I had seen some beading on the edge of one or 2 of the previous screens but nothing like this.

Also the first 12 I did all but the last 4 seemed to wash out pretty easy. Then the last 2 of those and the one good from this last batch took forever to wash out. They took so long actually that I reburned 2 screens thinking the screens had somehow gotten exposed before hand. I have them in a light tight frame rack I built under the exposure unit.

Any suggestions or thoughts are appreciated. I need to wash these 3 out and try again. I will try 1/1 on these 3 and see if I am just over coating them.

Thanks
Jon


Online aauusa

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Re: Screen prep problem
« Reply #1 on: April 18, 2019, 04:42:27 PM »
to much emulsion on the screen.  it dripped off on to the others.      some may say loose screen but it looks like they are tight in the pic.

many other will chime in but here is my .02 help on coating by hand

I use a glisten method,  meaning I coat on the shirt side until i see the emulsion start to glisten on the ink side of the screen.  when I see this I do 1 coat on the ink side, and done.  It make take 2,3,4 coats to get a glisten just depends on the pressure you are using and the black of your coater(round or sharp) edges and which side you are using.   I use the sharp edge. 

But I would increase your pressure on the screen when coating and this will help eliminate this issue regardless of how you decide to coat.   and when done right the emulsion is one shade through-out the screen.   you see on yours where the emulsion is light(thinner) in some areas.   

you can always over coat and then do a hard scrape to get excess off as well.   

Offline 3Deep

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Re: Screen prep problem
« Reply #2 on: April 18, 2019, 05:00:33 PM »
Are you using the sharp edge of the coater or round edge? and yes are the screen tight, loose screen mesh will cause that to happen every time.  what mesh screens are you coating anything below 110 might drip and do you use any type of air to help dry the screen.  The higher you stack a thick coated screen gravity will take over unless you have a fan or dryer blowing on them.
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Offline RICK STEFANICK

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Re: Screen prep problem
« Reply #3 on: April 18, 2019, 05:03:59 PM »
did you use a scoop coater?

Offline Maxie

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Re: Screen prep problem
« Reply #4 on: April 19, 2019, 04:57:35 AM »
Make sure you are using a coater.
Start off with 1/1 using the thin side. (You can increase thickness later)
Dry the screen flat, shirt side down. (It looks like you dried the screen standing up.
Looks like you have way too much emulsion and are not drying level.
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Offline BP

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Re: Screen prep problem
« Reply #5 on: April 19, 2019, 07:21:19 AM »
Jon, I really think you would be better off by paying someone to come to shop and teach you the craft of screen printing. All of these printing 101 problems will go away!
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Offline Jhtitan

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Re: Screen prep problem
« Reply #6 on: April 19, 2019, 08:26:40 AM »
Thanks all for the input.

So far we have stuck to the 150 -200 mesh screens. all screens are tight, at least they seem tight. I don't have a way to measure how tight they are.

I am using a scoop coater, I am not sure if I am using the sharp or round side honestly. I am using the side the previous owner had marked as "Use this side" with sharpie. I will check tonight and see if I can tell a difference.

I am drying them flat with the shirt side down. While my floor may not be completely level, it is a basement floor, they should at least be somewhere close level. I built a storage cabinet under the exposure unit. The cabinet was wrapped on 5 sides with black waterproof coated canvas. Ir is UV resistant and light tight. The doors are 2 flaps of the same with velcro around the edges. I am concerned with airflow. My next plan is to get a fan added to one side with some duct work and then an exhaust duct on the other side.

I have been doing 3 coats, ink side/ shirt side/ ink side. And the screens did not look like that when they went into the cabinet. they were clean with almost no streaks or lighter coated areas.

I will try 1/1 and see how that works out and I will also try to get some airflow into the cabinet, I may have gone a little overboard on making sure it was light tight and made it too air tight in the process.

Offline dsh

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Re: Screen prep problem
« Reply #7 on: April 19, 2019, 09:16:07 AM »
My granddaughter came for a visit and wanted to coat a couple screens.  The same thing happened.  I figured it was a lack of wrist strength and she didn't put enough pressure on the screen with the coater.  I'd say use the sharp side of the coater.  I've gotten the same kind of effect when using the wide side.

Offline inkman996

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Re: Screen prep problem
« Reply #8 on: April 19, 2019, 09:17:45 AM »
Is their high humidity in the room? If the emulsion does not start drying fast enough it will start to run like in the pictures. Moving air is really important to get them to start to dry, our screens have two fans pointed at them while drying.
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Online whitewater

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Re: Screen prep problem
« Reply #9 on: April 19, 2019, 09:56:36 AM »
seems no air flow in your cabinet and high humidity. I bet if you coat the screens and the leave the door open to the box and blow a fan in there it will help.. also being in the basement higher humidity, get a dehumidifier .  I know because I started in my basement 15 years ago.

Offline Prince Art

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Re: Screen prep problem
« Reply #10 on: April 19, 2019, 10:01:24 AM »

The difference between sharp and round side of the scoop coater can be massive. I've always used the sharp side; tried the round not long ago to experiment, and I had emulsion dripping & running everywhere.

If you're still getting too much emulsion, you could try coating 1 outside / 1 inside / scrape outside / scrape inside. (Medium pressure on the scrape.) Not most people's standard practice, but it's worked for me with high-solids photopolymer emulsion.
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Online Frog

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Re: Screen prep problem
« Reply #11 on: April 19, 2019, 10:31:21 AM »
Jhtitan, the first response to your post here mentioned the use of the "Glisten" method.
When coating a screen. for use with plastisol inks, this method all but eliminates many of the other variables.
Tried and true, check it out here http://www.theshirtboard.com/index.php/topic,2621.0.html
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Online Frog

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Re: Screen prep problem
« Reply #12 on: April 19, 2019, 11:05:46 AM »
The next issue that folks brought up here was the drying of the coated screens. Doug and his (our) friend John have you covered on that as well. https://www.vastex.com/Articles/Screen-Drying.php
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Offline Jhtitan

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Re: Screen prep problem
« Reply #13 on: April 19, 2019, 01:10:09 PM »
I ordered some fans to add to the bottom of my cabinet along with some exhaust venting near the top should fix the lack of airflow problem. I do know the second round I prepped we were trying to speed the drying time so I had opened one side a bit and set a fan pointed in along with a small gap on the other door to let the air out again. I am now thinking it may have been the lack of air flow mostly coupled with a bit too much on the screens. I will see how this works and let you know what I find.

I will look at adding a humidifier in there as well.

Not sure if it matters or not but we are using Chroma Blue emulsion.

Do the scoop coaters wear out at all? Other than damage from drops and such I mean.

We are going to see if a friend that is in the business can come over and take a look at everything for us. Just to make sure we are doing things the best way possible.

As always you guys are a great help!

Jon

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Re: Screen prep problem
« Reply #14 on: April 19, 2019, 01:44:45 PM »
I ordered some fans to add to the bottom of my cabinet along with some exhaust venting near the top should fix the lack of airflow problem.
Jon

Consider adding some filter material to the intake fans (and monitor its condition)
Otherwise, you are essentially making the cabinet itself act like the canister of a vacuum cleaner.
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