austiniv

ok. I really need help asap because I got ahead of myself and I have orders to fill already for shirts I advertised but can't get the freaking screens right!

I have been doing plastisol for years, have a very basic setup. I use a halogen bulb, expose for about 10 minutes and rarely ever have a problem washing out with a garden hose.

i am new to discharge but am using pro-chem swr3 emulsion and it seems to be a totally different exposure time. no matter what time I try it is extremely hard to wash out. 6 minutes is too short as I get "runs" and emulsion is obviously slimy and underexposed, however even at this time it's hard for anything to wash out except with a pressure washer and then all the emulsion goes fairly fast. at an 8-10 minute exposure it seems to be about done but again impossible to wash out except with extremely high pressure from the pressure washer which leads to pin holes and crappy edges.

what am I doing wrong?

I coat each side twice, dry horizontally, usually for at least 5 hours to be safe.

 

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studog79

For each different type of emulsion you need to do a step test to find the correct exposure time for your emulsion and exposure unit combination.

Also you should be using a power washer to blow out your image. This will give you the best screen for printing. Again do a step test to figure out your exposure time.

Also for discharge or water ase I would let the emulsion dry at least 24 hours before exposing your screen and using it for printing. Sometimes there is still some moisture in the emulsion and this will cause the screen to start breaking down fast.

Good luck and let me know if you have more questions.

__________________
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www.goliathpromo.com Goliath Promotions - Contract Screen Printing

 

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austiniv

Quote: Originally Posted by studog79 For each different type of emulsion you need to do a step test to find the correct exposure time for your emulsion and exposure unit combination. Also you should be using a power washer to blow out your image. This will give you the best screen for printing. Again do a step test to figure out your exposure time. Also for discharge or water ase I would let the emulsion dry at least 24 hours before exposing your screen and using it for printing. Sometimes there is still some moisture in the emulsion and this will cause the screen to start breaking down fast. Good luck and let me know if you have more questions.

thanks for the advice but like I said I am having the problem of the screen not breaking down enough even when I know I am underexposing it. I will try a step test, it didn't help much when I used it for my plastisol emulsion (trial and error proved to be more succesful) but I will try with this. I will also let my screens dry 24 hours and see if that does anything. but again, my screen is not washing out at all unless I do use the power washer and this is at even underexposed times. any other variables I am missing? thanks

 

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dye hard

First of all we need to know how photo-emulsions are being prepare, it is formed by two major polymers base, namely:
PVAc( Polyvinyl Acetate) and PVOH( Polyvinyl Alcohol) and water is their major verhicle and slight organic solvents for better durability and flexibility.

Distinguishes:
• PVAc is water resistance with a solid
content of 45~65% having thinner shear,
higher opaqusity with larger particles,
it make up of the major parts in most
P.emulsion formulation but it is not
solvent resistance.

• PVOH is opposite from PVAc with a solid
content of 15~30% having a more thicker
viscosity, more transparency and smaller
particles. Thats why SR P.emulsion is
having more clearity than WR P.emulsion.

Since SR P.emulsion is less water resistance and less light sensitivity, thats why you find it easier to handle with light exposure time and easier wash out then WR P.emulsion.

Again you need to know the PVAc solid content of your WR P.emulsion, the higher it is, the exposure time will have to go shorter, prepare your screen within an hour's time best with hot air blower, make sure it is under weak UV light source, do not leave the coated screen for too long hours in your stencil room, it may course unnecessary light disturbances.

Soak the ready stencil with water for about 10~15 mins before spray out the design part for printing. Remember water should be force out from the inner side rather from the outter screen, as this will help to minimise any further screen damaging.

Wipe the printing side with some micro fibre cloth before dry out with hot air, make sure the screen is fully dry before any job being carry out.

If U still having problems with exposing time, U may like to try this by mixing certain part of SR P.emulsion into WR P.emlusion say about 20~30%, and see what you get from the final results.

Note: This is only my experienced and as guidence. For further sceen performance, please check them out with your suppliers, they can provide better info to U.

 

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austiniv

Quote: Originally Posted by dye hard prepare your screen within an hour's time best with hot air blower, make sure it is under weak UV light source, do not leave the coated screen for too long hours in your stencil room, it may course unnecessary light disturbances. Soak the ready stencil with water for about 10~15 mins before spray out the design part for printing. Remember water should be force out from the inner side rather from the outter screen, as this will help to minimise any further screen damaging.

wow. I have never read or heard any advice like this. I will certainly give it a try. so maybe I am letting my screens dry too long? and I will try and really let the screen soak before trying to wash the image out. I've already let 5 screens dry over night so I am going to give them a try now but will try the soaking method. will post a reply update. thanks!

 

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dye hard

You are welcome, I will keep posting and update the technical data about ease of printing with water based inks on light fabrics, and high coverage inks on dark fabrics. You can always keep track on my post.

 

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austiniv

Quote: Originally Posted by dye hard You are welcome, I will keep posting and update the technical data about ease of printing with water based inks on light fabrics, and high coverage inks on dark fabrics. You can always keep track on my post.

so today I got a few screens I could use but not with ease. the step test showed that 10 minutes, like my plastisol emulsion, is optimum but I still have to use about 3/4 pressure on my pressure washer to wash the image out which I hate. I feel like I am going to blow out the whole screen doing this. but I did seem to manage to keep the images in tact in doing this today. it did take about 5-8 minutes of heavy pressure to accomplish this though which still doesn't seem right. but none the less I have something I can print with for now. any other advice would be much appreciated. thanks to you 2 that have responded so far.

 

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JerseyTrash

I've only been screenprinting for about 6 months, so I'm very much a beginner. I've only had one fallen soldier, so far. One way I like to speed up the 'blowing-out' time is by giving a 30 second spray on either side. Then, I place the screen face down on a FLAT, CLEAN counter and rub GENTLY the back of the screen with a damp cloth. Call me crazy, but it breaks up the emulsion and keeps crisp lines entact. Then I give it a good spraying from the back (like you're supposed to) and then wipe GENTLY, ONCE over the front of the screen (side you shouldn't touch) and rinse off the screen again, rubbing my hand across both sides. I treat my screens like babies. It's one of, if not the most, nail-biting parts of the entire process. Anyway, for me, this seems to quicken the time you're pressure washing. Hope you can use this idea in your process!

 

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