Emulsion Issues

Here you can discuss issues related to exposing screens for screen printing. This includes determining the exposure, light sources and washing out the stencil in the washout booth. Emulsion issues may also be addressed here.

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Crabsmen
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Emulsion Issues

Postby Crabsmen » Thu Dec 11, 2014 5:44 am

Hi Guys,
Im having a few problems with my screens, more specifically transferring my design into the screen. The problem is that when I wash off my emulsion I seem to be washing off random spots of emulsion on the screen.
Also just to help set the scene, I just bough a bunch of second hand screens and all the bits as I am just starting off, the screens were left with some old (really old) baked on emulsion that took me a solid hour of high pressure
washing and some helpful house hold chemicals to get off.
I let the screens dry then coated them in emulsion. I used a squeegee as I don't have a scoop coater as yet, and made the emulsion pretty thin so as not to get thick pockets, or areas. I left the screen in a box covered in some sheets
in my garage as to make sure no lights where damaging the emulsion. The screen sat for four to five days, and then when I did my screen burn and wash I seem get some funny results. I also noticed that it looked like the emulsion had ran
down the screen, although the screens where horizontal so I'm not sure if this happened during the waning off process. The emulsion I am using is Speedball (https://www.eckersleys.com.au/products/speedball-fabric-screen-printing-kit) and
its brand new.
Anyway I'm just winding if someone could be so kind as to point me in the direction of what I'm doing wrong. is it the chemicals I have used to clean the screen that is having an effect? (bathroom mould remover btw) or is it that my emulsion is too thin?
Currently where I am its around 90 Deg Fahrenheit with humidity over 70+ could this also be a factor ?


Also is there a secret for getting thin lines? My designs have numerous thin lines and they seem to be transferring on to the emulsion but are just being a bit difficult to wash out, and if I am successful in washing the emulsion out of the fine lines I also
manage to wash into areas that I would like to stay emuslion.




Image
Image


Thank you very much for all your help!


ApeShirt
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Re: Emulsion Issues

Postby ApeShirt » Thu Dec 11, 2014 7:57 am

I'll say it's probably a combination of things. First thing is that it's probably under exposed. Using household chemicals can leave behind residue that you don't want also. Having a scoop coater would also help achieve an even coat. You probably have some spots with thicker emulsion which might not be exposed long enough compared to the thinner parts. Line detail can be an issue of screen mesh count. Thinner/finer the line, the higher mesh you may need.
I strongly suggest you get some emulsion remover and degreaser. And a scoop coater! Plus, make certain the screens are completely dry before exposing. Having some airflow should help with that. I'd even add a dehumidifier to the area.
It may take a little "extras" for your setup to work but it can be done. Good luck and keep us posted.
Greg
If you're not going to go all the way then why bother going at all.
ApeShirt Apparel Printing, LLC

Crabsmen
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Joined: Thu Nov 27, 2014 8:32 pm

Re: Emulsion Issues

Postby Crabsmen » Thu Dec 11, 2014 2:40 pm

Thanks very much Apeshirt.
I am currently exposing on a light box with 3 fluro lights for 8mins, would you suggest maybe 10min or maybe more?
I will definitely be ordering a scoop coater, and some degreeser thank you very much for your help.

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Catspit Productions
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Re: Emulsion Issues

Postby Catspit Productions » Thu Dec 11, 2014 8:43 pm

I agree with Greg and I will add that excessive heat and high humidity can cause problems with screen exposures.
Jonathan Monaco
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ApeShirt
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Re: Emulsion Issues

Postby ApeShirt » Fri Dec 12, 2014 8:59 am

Interesting, J-money. Being in the north, I don't deal with real high humidity and temps generally. I had no idea those two things can affect exposing. Screens that is. I know some people have an urge to expose themselves when it gets hot out :o
I can't speak to how much longer to expose for as I have a different exposure unit. Maybe start with one minute longer and go from there. Keep in mind that times should vary with different mesh counts as well. Higher mesh holds less emulsion so they expose quicker. But for now, with what you are working with, that's not really relevant. Other than having an uneven coat of emulsion. It's tricky in your case because of the thick/thin areas. If you feel comfortable doing so, you could also try lightly rubbing your finger on the stencil area that is not washing out easily. Just do so while still washing out and careful to not rub too hard as to ruin the edges of the stencil. But don't take too long.
Greg
If you're not going to go all the way then why bother going at all.
ApeShirt Apparel Printing, LLC

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Catspit Productions
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Re: Emulsion Issues

Postby Catspit Productions » Fri Dec 12, 2014 9:14 am

Yes, Greg. High humidity will keep the emulsion saturated and perhaps prevent exposure. Also if it's very hot you can have the same type of issues. Sometimes even though screens may feel dry they still have high humidity and will not properly expose. This video covers that I believe.



For instance in the summer here in Phoenix when it is over 90 in the shop I cannot expose screens. They just don't expose properly. So I had to do all exposures early in the AM.

This article could help with getting detail.

http://www.catspitproductionsllc.com/hi ... ounts.html

Also he may want to consider switching emulsions. Not trying to sell here but the truth is a good emulsion can make all the difference and a lot of people have difficulties with the Speedball emulsions.

http://catspitscreenprintsupply.com/emulsion/
Jonathan Monaco
Catspit Productions, LLC
Learn how to screen print tee shirts!

http://catspitscreenprintsupply.com/
http://www.youtube.com/user/CatspitProductions

Crabsmen
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Joined: Thu Nov 27, 2014 8:32 pm

Re: Emulsion Issues

Postby Crabsmen » Fri Dec 12, 2014 7:13 pm

Hi Guys
Again thank you all for your help. I believe my mesh count on my screen to be 120T. I also have Fuji Dirasol 915 (http://product.fujifilm.com.au/dirasol-915#specifications) that I only mixed up last week,
but i believe it to be about a year or two old. So I'm not sure if it will still be any good.. Hey give it a go and ill find out quick enough I guess..
The temp and hunidity has finally dropped off for a bit here so I may get cracking and see if I can tell the difference.

And thanks for the article it makes a lot of sense. I do believe I may need to get a higher thread count. Could you recommend a good emulsion? for higher humidity areas?

Thanks again!!! :D

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Catspit Productions
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Re: Emulsion Issues

Postby Catspit Productions » Sat Dec 13, 2014 8:57 pm

You're very welcome. It's my pleasure to help out.

I might use the Textile PC Blue. I actually do and I find it to be a great all around emulsion. It will last up to 3 years or more in the bucket. No mixing needed.

http://catspitscreenprintsupply.com/saa ... on-gallon/

Also this article has mesh information including the conversions from Metric "T" to US standards.

http://www.catspitproductionsllc.com/sc ... sions.html

A 120T is like a 305 mesh here in the US. That is a very high mesh count.
Jonathan Monaco
Catspit Productions, LLC
Learn how to screen print tee shirts!

http://catspitscreenprintsupply.com/
http://www.youtube.com/user/CatspitProductions


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