karolina

Hi Guys -

How are you? I am having a similar problem... Being new I am expecting problems occuring along the way, but trying to do lots of research to avoid multiple mistakes...

Anyway, when washing off the emulsion, parts of the image won't wash out (very tiny parts - almost gives it an faded look). For this project, I would prefer a crisp image, but I suppose it's not terrible for my second try. Do you have an idea of what is causing this?

My second problem is also when I'm washing off the emulsion. I do it right after exposing/burning the image (using one of those PVC units from silkscreeningsupplies.com). Some of the emulsion (especially in the corner areas, where the emulsion is thicker) turns gooey and I worry it will rub off when touched. My exposure time is about 13 minutes...

Lastly, I was hoping for some advise on how much emulsion to put on. Should I try to get a very thin layer? Is that key? I have problems using the "scooper" - It seems to put a really thick coat on, which means I have to empty the scooper and run it over the screen several times to take off the excess. Doesn't seem right.

Please help me - I appreciate all advise!!!

Thanks a ton & have a great evening ~ Karolina

 

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brent smith

hello karolina , ifyou are having trouble washing out fine detail or small portions of your art try a shorter exposure time. it makes a big difference if you are using white or yellow mesh. sound like you are over exposing which is real easy to do in the beginning. #2 dont worry about the gooey part as you screen dries it will harden right up .#3your coater should have a fat side and a thin side, when coating 110's on down to 60's after you coat them you have to go back and clean them up , which means scrapping the excess off with your coater just dont tip it to where the emulsion touches your screen ,you use the coater to scrap up your screen just like you were coating just dont tip the coater, as you come up the screen you will see all the excess coming off, and yes you want a thin coat. 90% of the time. good luck and keep trying

 

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RichardGreaves

Quote: Originally Posted by karolina .... when washing off the emulsion, parts of the image won't wash out (very tiny parts - almost gives it an faded look). For this project, I would prefer a crisp image, but I suppose it's not terrible for my second try. Do you have an idea of what is causing this?

Search the forum for "exposure test". You have to learn to make a stepped exposure test which is like cutting a hamburger in to slices and cooking each slice a different time until you find the exposure you like.

Emulsion is easy: If the emulsion washes out - it wasn't exposed to UV energy. If it doesn't wash out, it was exposed to UV energy or heat and cross linked somehow. The two factors of exposure are complete cross link, for the most resistance AND how much exposure with each combination of mesh, stencil and exposure before the finest line you want to print closes up.

For your next exposure, tape a dime to the stencil to see if the dark areas of your positive are failing you and letting UV-A energy through to the stencil. If the area covered by the dime doesn't wash out, you have exposed the stencil to UV energy or heat energy and the stencil is resisting dissolving with water and going down the drain.

emulsion + exposure newbie help


Support Menu of Screen Making Products

Here is a link to a 2 minute video you can download and watch over and over. When you get tired of wasting time guessing about exposure, call your supplier and buy an exposure calculator ($35), and 21 step transmission gray scale ($10). Properly used, they will last a life time.

Quote: Originally Posted by karolina I was hoping for some advise on how much emulsion to put on.

I have a post with pictures to describe coating mesh with emulsion.
Too much pressure or Screen mesh too high?

How much? Enough to form a film on the bottom of the mesh that will create a gasket and crisp edge that controls your ink.

I want you to use an emulsion trough with a rounded (2mm) thick edge.

Use the rounded edge for initial coats. Keep the coater filled with emulsion so there is liquid pressure and you don't have to wait as you tip the coater against the screen and start to coat.

Remember, the emulsion ends up on the other side of the mesh that you are coating because there are holes in the mesh.

Tip the coater against the mesh until the liquid touches all the way across the edge.

With a slow, even stroke, coat the mesh. Slow and stop before you get to the top and roll you hands back, then scrape the last little bit, back into the coater.

No one can tell you how many times to coat.
No one can tell you how many times to coat.

You have to check to see if you have pushed enough emulsion through the mesh for it to link up on the other side and make a smooth, glass like finish on the squeegee side of the screen.

If you haven't pushed emulsion completely through the holes, WHEN YOU COAT THE INSIDE OF THE MESH, YOU WILL TRAP AIR IN THE STENCIL.


Now turn the screen around and make a final coat on the squeegee side of the mesh and it will push all the emulsion through the mesh to the stencil side where all the work will be done.

Emulsion is mostly water that must evaporate befor you can expost the screen. As the water leaves the film it shrinks and takes on the rough shape of the mesh.

If you want a smooth gasket to control the ink, you should add a face coat to the stencil side (it doesn't help to add more emulsion to the squeegee side) with the SHARP end of the squeegee.

While you are at it, try an experiment. Coat a screen with the rounded edge until it is glossy in the inside. Take another screen of the same mesh and coat with the sharp edge until it matches the round edge.

You will find it take many many more coats to equal the round edge.

__________________
How are you measuring? retired Ulano Technical Support
Screen printing since 1979 - SGIA Academy Member

 

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