I am new to screen printing, and actually this is my first post on this website. I've been visiting this website for awhile now and it has helped me out A LOT, whether I went here for knowledge of certain things or just for what people thought on certain things I wanted to purchase. Thank You t- shirtforums.com.
Now down to the reason I'm posting-
About how long should I expose a 110 screen, with a 1-2 and 1-2 coat of CCI Pro Chem SWR-3 (Water Resist Emulsion) using a 500 watt halogen light with the glass still on the light?
Thx
P.S.-- Please dont use this thread to ask your own questions, atleast until further notice. (Like if I'm satisfied with the answer(s) and your question is in this same category)
every setup will have a different exposure time.
but with a 500 watt halogen i would start around 10 min..
and is there a reason you have to leave the glass on the light, because it reduces a lot of the UV energy?
you should try doing a step wedge test..
the link above is a tutorial on how to do one and it also has a graphic to use as well..
good luck, woodward
Actually I have no reason to leave the glass on, but wouldnt it be safer?
So is it start around 10 minutes with glass or without it?
And the emulsion I'm using has a paper that came with it that says something about expose 360 secs (6 mins) with 40 watt fluorescent is that a way to determine the time with a halogen light source?
And the step wedge system, I don't really understand how that works if you don't mind explaining a bit.
it will be safe with the glass off, just don't look at the bulb directly or leave anything super close to the bulb. and yes, 10min with the glass off. the reason they don't list an approx. exposure time is because a 500 watt halogen isn't an industry standard.
when you preform a step wedge test, your basically trying to expose a design multiple times on one screen at different time increments to see which time is best.
if you look at the image, you will see 8 columns of a repeated design. your going to expose each column a different amount of time.
first you think of an approx. exposure time, 10 min. then you multiply that by 1.5=15min. divide 15 by 8(# of steps) and you get 1 min and 42 sec.
so you will expose each column for 1:52 using a piece of card board to cover the steps that are waiting to be exposed. after you expose a step, Don't cover it back up. when your finished you will get multiple exposures from 1:52 secs to 15:00 min..
if im too confusing the link should be able to explain things better How to Determine correct screen exposure times using Vellum
i hope this helps, sorry for the essay..
woodward
it will be safe with the glass off, just don't look at the bulb directly or leave anything super close to the bulb. and yes, 10min with the glass off. the reason they don't list an approx. exposure time is because a 500 watt halogen isn't an industry standard.
when you preform a step wedge test, your basically trying to expose a design multiple times on one screen at different time increments to see which time is best.
if you look at the image, you will see 8 columns of a repeated design. your going to expose each column a different amount of time.
first you think of an approx. exposure time, 10 min. then you multiply that by 1.5=15min. divide 15 by 8(# of steps) and you get 1 min and 42 sec.
so you will expose each column for 1:52 using a piece of card board to cover the steps that are waiting to be exposed. after you expose a step, Don't cover it back up. when your finished you will get multiple exposures from 1:52 secs to 15:00 min..
if im too confusing the link should be able to explain things better How to Determine correct screen exposure times using Vellum
i hope this helps, sorry for the essay..
woodward
Thank you so much.
Sorry for essay!?
Look, whether its a sentence or something two pages long, if it's helpful, it's helpful. Period
A good place to start is the distributor you bought from - then the manufacturer. It is true, I don't think any emulsion manufacturer lists a quartz halogen lamp because there are so many different manufacturer's lamps with unique UV energy output.
Quartz halogen lamps are designed for visible light and like all filament lamps they are very hot. That's why they are made from quartz glass - not regular glass. The heat is from all that invisible Infra Red energy which is at the opposite of the visible light spectrum from the in visible UV-A energy we need to react with photo sensitizers in the emulsion. There is some usable invisible UV energy and quartz halogen lamps are very popular for people on a budget, but it's like hiding a case of beer in a swimming pool. You have to handle an awful lot of pool water to get to the beer.
UV energy is discouraged in quartz halogen lamps used in the house because wall paint, drapes and upholstery fade and discolor. That's why you often see protective coatings on lamps and safety glass to protect your eyes.
You need to perform an exposure test. If I came to your shop, I would still need to perform an exposure test on a coating of emulsion only as big as a dollar bill, and after one exposure, I could calculate a minimum exposure to hold the stencil in the mesh.
I suggest a transparent 1 inch by 6 inch Stouffer 21 Step Gray scale. It is a photo positive that has 21 different 'neutral' filters so 1 exposure simulates 21 different exposures. You will get visual feedback from every exposure like a speedometer. It costs US$6 to US$12 and properly used should last a life time.
Search this forum for "exposure test" or "21 step".
Search this forum for "quartz halogen".
Only remove the UV protective safety glass if you want faster exposures.
How Long Should I Expose 
Re: How Long Should I Expose 
Re: How Long Should I Expose 
