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DougieN13 · June 23rd, 2008

I am new to screen printing, and coated a few screens and exposed them for quite a long time (20 mins) under my exposure unit, when i take it to the wash out i can see my design on the screen but when i wash the emulsion off bits round the edge of the design are flaking off

what am i doing wrong?

does it mean the screens are not dryed properly before i expose them?

any help would be great

am getting disheartened with it : [

brent · June 23rd, 2008

Don't get disheartened. You are new. I knew nothing when I started, now people call me for advice. You'll learn as you go, there's just a lot to learn!

Anyway, your screens may have been greasy when you coated them, so the emulsion didn't stick well. Try a degreaser before you coat them.

It also might not have been dried properly, possibly dried only on the outside of the emulsion, not the inner part on the mesh. Try letting them dry longer.

Does your film/transparency have nice clean crisp lines of the design, or is it sort of fading? Nice sharp edges burn best.

How are you burning? did you build a unit? If so, what's it like?

Sheepsalt · June 23rd, 2008

20 mins is a long time, even if you're using a halogen bulb.

There are so many variables, so if you could post exactly what you are doing it would help nail down where the exact problem may be.

Stuart's advice was spot on, too.

1. Start with a fully-opaque film - you should see no light through the print on the film when you hold it up to a light.

2. You need to thoroughly degrease your screens before you coat them. Scrub them with a degreaser using a pad or brush that you only use for degreasing. Scrub both sides for several minutes, going in every direction, and make sure you rinse them very thoroughly. Then make sure they are 100% bone dry before you move on - put a fan on the screen and leave it for quite a while. Don't touch the mesh with your fingers at all once they have been degreased.

3. Coat both sides of the screen with emulsion using a scoop coater, and set the screen horizontally to dry. Again, put a fan on low to blow air across the screen as it dries. Best to let them sit for several hours, maybe more depending on the relative humidity where you live.

4. Make sure your film is held flat against the screen and can't move during exposure. Tape it in place with clear tape. What type of exposure unit are you using? What type of emulsion are you using?

5. Rinse out the stencil - wet both sides of the screen, wait 30 seconds, then spray out the stencil area spraying from the shirt side. A garden hose with a good spray nozzle works pretty good for most emulsions. If you're using a pressure washer, make sure you're not getting the nozzle right up close to the screen. The emulsion is a bit soft from the water, and can blow out with enough pressure even where there was exposure.

Again, it will help to know exactly what you're doing now and what products you're using, but definitely don't get discouraged... just keep learning!

DougieN13 · June 24th, 2008

Quote:

Originally Posted by brent


	Don't get disheartened. You are new. I knew nothing when I started, now people call me for advice. You'll learn as you go, there's just a lot to learn! Anyway, your screens may have been greasy when you coated them, so the emulsion didn't stick well. Try a degreaser before you coat them. It also might not have been dried properly, possibly dried only on the outside of the emulsion, not the inner part on the mesh. Try letting them dry longer. Does your film/transparency have nice clean crisp lines of the design, or is it sort of fading? Nice sharp edges burn best. How are you burning? did you build a unit? If so, what's it like?

i am using this exposure unit
Wicked Printing Stuff Website

i did think 20 minutes is a bit long

i managed to do a successful one lastnight, i had left the screens to dry longer and it helped lots, also from reading up on different threads i didnt realise the emulsion comes off where the design is more from the mixing of the water and the emulsion rather than the pressure of the water, so i took more time washin it out at a less pressure and seemed to work better.

Thanks for your help mate

DougieN13 · June 24th, 2008

Quote:

Originally Posted by Sheepsalt


	20 mins is a long time, even if you're using a halogen bulb. There are so many variables, so if you could post exactly what you are doing it would help nail down where the exact problem may be. Stuart's advice was spot on, too. 1. Start with a fully-opaque film - you should see no light through the print on the film when you hold it up to a light. 2. You need to thoroughly degrease your screens before you coat them. Scrub them with a degreaser using a pad or brush that you only use for degreasing. Scrub both sides for several minutes, going in every direction, and make sure you rinse them very thoroughly. Then make sure they are 100% bone dry before you move on - put a fan on the screen and leave it for quite a while. Don't touch the mesh with your fingers at all once they have been degreased. 3. Coat both sides of the screen with emulsion using a scoop coater, and set the screen horizontally to dry. Again, put a fan on low to blow air across the screen as it dries. Best to let them sit for several hours, maybe more depending on the relative humidity where you live. 4. Make sure your film is held flat against the screen and can't move during exposure. Tape it in place with clear tape. What type of exposure unit are you using? What type of emulsion are you using? 5. Rinse out the stencil - wet both sides of the screen, wait 30 seconds, then spray out the stencil area spraying from the shirt side. A garden hose with a good spray nozzle works pretty good for most emulsions. If you're using a pressure washer, make sure you're not getting the nozzle right up close to the screen. The emulsion is a bit soft from the water, and can blow out with enough pressure even where there was exposure. Again, it will help to know exactly what you're doing now and what products you're using, but definitely don't get discouraged... just keep learning!

thanks for the information, i didnt realise that degreasing the screen so much was so important

my emulsion and exposure unit was from this website Wicked Printing Stuff Website

il keep practicing, the screens are getting better each time

Sheepsalt · June 25th, 2008

Looks like you've got a 1,000 watt halogen bulb for exposure - if you're using a dual-cure diazo type emulsion it shouldn't take more than 12 1/2 minutes. Shorter for higher mesh counts.

DougieN13 · June 25th, 2008

Quote:

Originally Posted by Sheepsalt


	Looks like you've got a 1,000 watt halogen bulb for exposure - if you're using a dual-cure diazo type emulsion it shouldn't take more than 12 1/2 minutes. Shorter for higher mesh counts.

ah il try 12 minutes

iv done a couple of successful screens now with 18-20 mins

what happens if you over expose?
do you lose detail in the design?
my designs have been pretty plain so far

Scott747 · June 25th, 2008

Make sure and do one of the exposure tests to make sure you have the correct timing...

Nietzsche · October 7th, 2009

I too am new to this business and run into questions on about everything I do. For instance:My transparencies are sticking to my screen after I burn them and pulling the ink off my transparancies. How do I prevent this from happening?
Thanks

moffett8 · October 23rd, 2009

Let the screen try longer. You are not letting the screen dry long enough. Try using a fan or a small electric heater to help speed the drying process just don't put the heater too close.

Philip

Nietzsche · October 23rd, 2009

Thank you for the info. Since I started having this problem I've revamped my dark room. I now have a de-humidifier and a set of fans in the room. It has helped in the biggest way.
Thanks again.

rcuellar1 · August 19th, 2010

hi an any one help i just started to do screen printing by watching videos on youtube. i put emulsion on the screen let it dry for a whole night and then burned my image.for 5 min with a plate maker burner machine when removed no image appears on the screen and when i wash out the whole emulsion washes off what am i doing wrong or is there anything else i need to add to the emulsion pls help as i dont know what to do can u all tell me where to buy the cheapest blank t shirt i dont have a tax id cause im not registered i have it in my garage thanks

chasamax · September 17th, 2010

Quote:

Originally Posted by rcuellar1


	hi an any one help i just started to do screen printing by watching videos on youtube. i put emulsion on the screen let it dry for a whole night and then burned my image.for 5 min with a plate maker burner machine when removed no image appears on the screen and when i wash out the whole emulsion washes off what am i doing wrong or is there anything else i need to add to the emulsion pls help as i dont know what to do can u all tell me where to buy the cheapest blank t shirt i dont have a tax id cause im not registered i have it in my garage thanks

I could attempt to lend a hand but it would be very difficult to pinpoint a single problem. If you have watched videos on Youtube than you probably realized that they don't use a plate maker burner for exposure ( I tried searching to see what that even is but to no avail). I would surely start there.

1. If you are on a budget, try picking up a halogen work light.. they are pretty cheap at your local hardware store. I don't use one but there are a lot of people on here that do, and I am sure they can assist with some sort of exposure time.

2. In regards to cheap t-shirts, t-shirtwholesaler.com is decent..

3. And the emulsion washing off could be numerous factors but what it sounds like to me is exposure time. I use a 6 - 15 watt unfiltered uv black light exposure unit and my average exposure time is about 8 1/2 minutes - your using a 'plate maker burner machine' so the exposure time should be somewhere between three days to literally burning your image onto your screen.

4. Also, what are you using to make your positives (images)?

I would probably type less but I have pulled an all-nighter on a print job.. so I am rambling.

Lastly, anything Richard Greaves posts in these forums you should search for and read... he's helped me a ton just by his posts. Some day I am going to send him a plate of cookies, don't worry Mr. Greaves, my wife will make them.

foot print · September 17th, 2010

Quote:

Originally Posted by Nietzsche


	I too am new to this business and run into questions on about everything I do. For instance:My transparencies are sticking to my screen after I burn them and pulling the ink off my transparancies. How do I prevent this from happening? Thanks

lets your films dry longer...what side of the film are you printing on..? Films have to sides a smooth side and the side with a little bit of texture...make sure you print on the side that has a little bit of texture. What type of film do you use...? I use Fixxons film that stuff is great and at a great price. Also make sure your coated screens are dried completely. I use a small space heater inside a drying box i made really speeds up the process.

chasamax · September 18th, 2010

I am going to step out on a limb and say the problem isn't with his films, but with his 'not very dry' emulsion.

If you are using an inkjet printer and you print on the wrong side you will typically get really wet ink that essentially pools on the surface. The best way to check on which side you need to print on is by licking your thumb and pointer and grab the transparency.. the finger that sticks is the side you print on.

Ok, back to the sticky positive - if your emulsion isn't dried enough, your positive will stick to it and not only did you potentially ruin your positive but you also wasted emulsion, cleaning supplies, and lots of time.

Make sure your screens dry overnight in a controlled environment if possible - and make sure you use a 21-step strip when exposing, it will save you a ton of money in the long run.

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