ok, i have been looking into getting into screen printing for the past couple weeks, well today i decided to buy a starter kit at my local hobby lobby to get a taste of it. (specifically i got the speedball super value fabric screen printing kit http://shop.vendio.com/artsupplysour.../?s=1185789603 )
well so far it hasn't turned out so well. i have done 2 screens (i bought an extra as i was planning on a 2 color print) and both were unsuccessful. i think my problem is coming when i burn my screens, but i will describe several things i noticed.
1.when coating emulsion on the screen, it is extremely uneven and seems thin, i have watched about 4 or 5 different tutorial videos on screen printing, and their coating seemed much thicker. i have had to use a squeegee to spread the emulsion because i couldnt find a scoop coater anywhere but the internet. also the emulsion sensitizer mix might be a problem, i followed the instructions, but there was still some crud left in the bottom of the small bottle.
2.i let the screens dry in a dark place with a fan running directly over them and they have dried extremely fast, i started burning them immediatly after they were dry and matte looking, they were dry to the touch.
3. i burned both screens for 1 1/2 hours thinking it would surely be long enough. i also used 2 different light sources. 1 standard 60 watt house bulb with a pie tin to reflect light, i hung it 12" from the surface of the screen, and 1 standard fish tank light (idk the watt, or anything, but it is deffinatly brighter/hotter) with the same details as the light bulb. i am fairly handy, are there any online instructions to build a light box out there that would give me A. shorter exposure times and B. more exact exposure times. i dont have a lot of money to spend at this time, so making my own is my best bet. when i say i dont have money, buying the kit, an extra screen, and a few inks left me broke.
4. when i took off my transparency, the emulsion was blue, and the parts covered by the black portions of my design were greenish yellow. i could clearly see the design.
5. when washing out the screen, both exposed and unexposed portions do absolutely nothing for at least 3 or 4 minutes, then all of a sudden the unexposed portion (the actual design) will start to wash out, then instantly after that, the emulsion around the design starts braking up and chipping off, ruining the design. so i just rinsed out the entire screen and cleaned it with the emulsion remover.
so what i would like to know is what i am doing wrong, how to fix it, and what i can do better (without spending money on expensive equiptment) please help me out, i need to get this down so i can start working with a friend screen printing in a month as a business. also if you need more info or details, just ask.
sounds like your l;ight source is the culprit and you actually didnt expose the screens properly.
Try a forums search for exposure units and exposing. Should come across a ton of info. Also a search for posts by Richard Greaves will get you tons of exposing info as well as exposure lights
if they were over exposed water would not make the emulsion fall or flak off.
Could also be that they were not truly dry. Just to touch doesn't mean the entire film of emulsion is totally dry. Some have to wait a full 24 hours to dry completely.
thanks for your help. i have just coated my screens again and i will let them lie until tomorrow.
i think todays project will be to find some stronger light bulbs and build some sort of exposure unit. i am going to search and find out the basics of exposure units.
once again thanks for your help, and any other sugguestions or solutions are appreciated.
Gator , right now I use a 500w halogen shop light from the hardware store,I place it about 30 '' abve the screen.It takes 12-13 mins. to burn. You can use 2 and put them together and cut your burn time.Im in no hurry so I dont mind 12 mins for now.JUst make sure you remove the glass lens that covers the box that holds the bulb as these lenses have a UV protector type filter.
They Are cheap (about the same prices as a dzn.Kraft dinners).
It does take a few mins. to washout after the burn process.Hope this helps and good luck.
i tried halogens for a while, from what i understand is they make a TON of heat but not much UV(lower end of the spectrum), which is what's doing the exposing.
i guess the heat "exposes" the entire screen instead of just the image to make it hard to wash out. i don't know much about professional units, i think some do use halogen, but it must be brighter, from far away to keep the heat off and to not undercut the image.
your screens should wash out in just a few minutes with normal pressure.
i think that is my project for this weekend. i will just make an 18" tall wooden box, paint the insides white, then set up the lights. it looks like the glass was the most costly portion of your box, do you think lexan or plexi glass could stand up to that, it is cheaper if i remember correctly.
the insides don't matter i don't think, they were already white.
plex or lexan might scratch too easliy, the scratches will burn into the screen. i've never tried it though, so it might work. it'd have to be thicker than glass or it will sag.
Just gotta make sure the uvs pass thru.Just a sheet of inexpensive stuff.We use lexan and plexi in the sign shop and am sure they filter uvs.I use a piece of cheap glass that used to cover a cheap print from a scond hand store.Just b cautious as i almost broke it once and it might of been serious.
i did some research and lexan/plexiglass does filter uv's and it does scratch very easily, so i will just get the cheapest pane of glass i can. i will just be careful around it like you said.
i did some research and lexan/plexiglass does filter uv's and it does scratch very easily, so i will just get the cheapest pane of glass i can. i will just be careful around it like you said.
Gator, sounds like your not exposing your screens long enough (well, also not using a strong enough light source). A single 500 watt shop light, front glass lens taken off, at about 16 inches about the screen will work fine. A 110 mesh should take about 8 minutes to expose properly at those specs. Washing out the image shouldn't take 3-5minutes, it takes us 15-20 seconds for the image to wash out, and to get the "crusties" out, we wash for another minute.
Do use a non uv repellent glass when exposing a screen to press the transparency onto the screen, but do becareful like the post above says. I broke mine at the shop the other week in half by holding it on one end too hard, and cut both my hands and shattered glass everywhere.
Scoop Coater is a trademark of the old Advance Process Supply. The name is now held by Advance World Trade, the son of one of the owners.
The proper generic term would be emulsion coater. Search for 'emulsion coater' in this forum. The last search hit is actually called scoop coater, and has my detailed instructions.
I don't like the Scoop Coater, it only has a .5mm sharp edge, not a rounded 2mm edge and you will have to make many more coats to build up emulsion.
A little sensitizer crud means you didn't mix it completely. Use the container to measure the correct water ratio, then shake it up in a clear glass jar with a screw lid so you can see when it is perfectly mixed.
There is little or no UV-A energy in an incandescent lamp. Search this forum for 'exposure lamp'.
Hot is usually a necessity, but any light you can 'see' is wasted. UV-A radiation is invisible to the human eye.
You did get some reaction as the yellow diazo sensitizer, but not enough!
If the stencil washes out, it wasn't exposed to enough UV-A energy and not enough cross linking occurred and the stencil dissolved and went down the drain.
ok, after 3 hours work and $80 in supplies/lightbulbs i have completed my homemade light box, i got the 90 watt day bulbs (they were $8 for a 2 pack, and the 75's were $7.25 for one, and the 100 watts were $8.70 for 1. what can i say, i am cheap) i am doing my first exposure now, i am letting it go for 10 minuits at 12 inches. so we will see how it goes.
edit: uh oh, the screen has been exposed for at least 45 minuits (not continuously) and no image has shown on the screen! i have had the screens sitting in a closet since Wednesday with a fan running over them. the fan ran until friday. is the emulsion on the screen ruined? help!
Last edited by gator50; August 5th, 2007 at 06:13 PM.
If the screen was in daylight you might have to reclaim /recoat.
if the screens were in a darkroom with a fan on they should still be good.
I wonder if you bought the right kind of bulbs?
even gro-lights should work(Ive never used them but heard they work)
80.00bucks? Mines primitive but was free,Borrowed the 20$ light source from my landlord =)
new and need help, screens arent turning out 
