# Cover just one side of screen with emulsion



## James007 (Oct 11, 2008)

Hi,

I was told from the guy who I bought my screen printing equipment etc. from that when applying the emulsion to the screen that you only have to apply it to the shirt side and not the ink side and I saw him just emulsion the outside of the screen and he then exposed it and it seemed ok. But can this cause problems or does anyone emulsion just the shirt side of the screen with one coat.


Cheers


Jimmy


----------



## lancelot (Jun 1, 2007)

Hi james,you will get a much better result if you coat both sides ,coat the shirt side first, flip, and then the squeegee side second,and when she is drying, lay the screen ,shirt side down (so the emulsion slumps and drys it is on the shirt side). The problem with coating on one side only is that the emulsion is very thin,you will get more pin holes after exposure and have to block out and you will find if your run is large you will be constantly stoping to put little bits of tape on your screen. from areas of ink finding it's way through the thin film.


----------



## James007 (Oct 11, 2008)

Thankyou. I did notice a few pin holes on the screen when I put it up to the light.

Thanks again 


Jimmy


----------



## jmlampert23 (Nov 7, 2008)

lancelot said:


> Hi james,you will get a much better result if you coat both sides ,coat the shirt side first, flip, and then the squeegee side second,and when she is drying, lay the screen ,shirt side down (so the emulsion slumps and drys it is on the shirt side). The problem with coating on one side only is that the emulsion is very thin,you will get more pin holes after exposure and have to block out and you will find if your run is large you will be constantly stoping to put little bits of tape on your screen. from areas of ink finding it's way through the thin film.


very well said. also when you let it dry shirt side down it creates a thicker layer of emulsion on the shirt side which makes a better stencil and will leave a better ink deposit on the substrate


----------



## stooky.design (Mar 13, 2008)

still got pin hole even though emulsion on the both side of the screen...but it less than when i put single side..


----------



## jmlampert23 (Nov 7, 2008)

you probably have some pin sized marks on your films. if you have a light table check your films.


----------



## JeridHill (Feb 8, 2006)

stooky.design said:


> still got pin hole even though emulsion on the both side of the screen...but it less than when i put single side..


A couple methods work extremely well. Coat the print side, then the squeegee side, then the print side again. For longer runs, do the same thing, then after it dries, coat both sides one more time.

This gives you a clean screen, but the more emulsion you put on your screen, the more time you need to add to burn effectively.


----------



## James007 (Oct 11, 2008)

Hi, Thanks for the info. At the minute I coat 1 side and the expose for 6 - 8 minutes. So if I coat both side does that mean I would have to do maybe 10 - 12 minutes.

Also does it make it hard to decoat/reclaim the screen.

Cheers


Jimmy


----------



## JeridHill (Feb 8, 2006)

James007 said:


> Hi, Thanks for the info. At the minute I coat 1 side and the expose for 6 - 8 minutes. So if I coat both side does that mean I would have to do maybe 10 - 12 minutes.
> 
> Also does it make it hard to decoat/reclaim the screen.
> 
> ...


No you wouldn't have to double your exposure time, you would just need to increase by a little. It also depends on your exposure setup. If you are getting a good burn, I would just increase by a minute and see where you are. You may be ok. My setup has always been, 2 sides coating, 1 the other, but with the emulsions and my setup, it takes 2 1/2 minutes to expose. So you will just need to play with it.

You may also try keeping it at the same exposure time to see how it will work for you. A step wedge is also something that would be beneficial to you, this will give you accurate time settings for your setup. I would do a quick search on this site for step wedge, you should find quite a bit of info on it.


----------



## staned (Feb 25, 2007)

i'm sure richard greaves will chime in but this is what works for me. three coats squeegee side to fill the mesh. one coat shirt side to cut off the uneven emulsion caused by ghosting and staining in the mesh, then one more squeegee side stroke to move the glossy look to the bottom of the screen. the bottom of the screen is where you want the emulsion gasket. they must dry bottom down. my hand can feel an under exposed screen during rinse out of the design and i adjust. i have a giant exposer unit and several test films. but find my hand works fine to tell me when it's cooked enough. stan


----------



## James007 (Oct 11, 2008)

So just to check does everyone dry the screens t shirt side down.? As I have been drying them after applying the emulsion squeegeeside down as I didnt want anything to touch the tshirt side emulsion.?

Cheers

Jimmy


----------



## tdigital (Sep 14, 2008)

Yes T-Shirt / Print side down


----------



## RichardGreaves (Nov 7, 2006)

Stanley called my name and I rose from my slumber....

I don't like to suggest any specific number of strokes with a coater because of the variables, but I do have reasons for my method.

1. The mesh has holes in it. We don't actually coat, we push emulsion into the holes. That zither like sound when you coat is the trough scraping the mesh. No frosting here! Emulsion ends up on the other side. That is why you you should start on the bottom and finish on the inside, so the emulsion ends up where it belongs - on the bottom.

2. Emulsion is mostly water that has to evaporate when it dries. If you have 38% solids, you have 62% water. When the water evaporates, the film takes on the shape of the mesh which can look like a waffle. For fluffy textiles, this doesn't matter much, but on non absorbent products like glass, metal or plastic you get edges that look like a saw. (Saw Tooth). Even if you fill the mesh openings completely, it will only have 38% solids when it is dry. This is like a tax from Mother Nature.

3. You should use a rounded lip coater (2mm). A sharp edge lip (.5 mm) will have a very hard time pushing emulsion into the holes to fill them. I have a page on the Ulano web site showing 6 strokes with a rounded and sharp edge trough. The sharp edge never forms a glossy coating on the inside of the mesh. Coating FAQ of Screen Making Products

4. A glossy inside proves you have completely filled the holes from the bottom of the screen. When you turn the screen around, *there are no holes to trap air* (pinholes of the future), as you make your final coats from the inside to create stencil depth. How can you have pinholes if you have filled the holes with emulsion?

5. Emulsion on the inside of the screen is helpful to make a more durable stencil, (like a watch band), but, it's the stencil on the bottom that controls the image. Dry your screen so gravity can help pull the liquid to where it belongs. Emulsion doesn't know how it was coated on the mesh, but as a liquid, it does respond to gravity as it dries.

6. Too much final coating from the inside can cause drips. A thicker coating may be your target, but the mesh is what should be used to determine ink deposit, not the stencil - except when you are making a super thick stencil for special effects inks.

7. If you are keeping your emulsion cool by putting it in the refrigerator because it is the only place you can think of that is cooler than your coating room, at 42°F you are 10°F from ice cream. If you coat with cold emulsion, when it warms as it dries - it will drip.

8. A coating experiment costs nothing. Coat 3 times from the inside at different lengths like I show on the coating support page of the Ulano site and test the difference. Yes, a thicker more durable stencil will take longer to dry and longer to expose fully. 

There are thousands of ways to coat. These are _*rules with reasons*_ to prevent something undesirable. You all know you can skip or shortcut these steps, and if it works, you win. If not, these would be the fundamentals.


----------



## James007 (Oct 11, 2008)

Thanks for that, I will continue to do more tests this week, even if it takes forever I will get it right.

Cheers 

Jimmy


----------



## C-DUB (May 7, 2008)

RichardGreaves said:


> 7. If you are keeping your emulsion cool by putting it in the refrigerator because it is the only place you can think of that is cooler than your coating room, at 42°F you are 10°F from ice cream. If you coat with cold emulsion, when it warms as it dries - it will drip.


Thanks, I was wondering about this. I was getting a lot of drips until I let the emulsion warm back up to room temperature before I coated screens.

Invaluable information! Thanks for the post Richard.


----------



## treadhead (Jul 26, 2006)

lancelot said:


> Hi james,you will get a much better result if you coat both sides ,coat the shirt side first, flip, and then the squeegee side second,and when she is drying, lay the screen ,shirt side down (so the emulsion slumps and drys it is on the shirt side). The problem with coating on one side only is that the emulsion is very thin,you will get more pin holes after exposure and have to block out and you will find if your run is large you will be constantly stoping to put little bits of tape on your screen. from areas of ink finding it's way through the thin film.


This explains exactly what I am running into. Excellent info! I only coat the squeegee side and do find pinholes at times and then they seem to "come out of nowhere" during the run.

I currently expose my screens for 5 minutes with one side. How much longer would you recommend if I coated both sides? An extra minute or so?

John


----------



## staned (Feb 25, 2007)

if you dry your screens on end the emulsion will run to the bottom. you my know that, but did you know that the same thing is happening to the windows in your house? yes glass is a very slow (viscous) liquid and gets thinner at the top and thicker at the bottom over time. don't bother watching, it takes awhile. stan


----------

