[heatdvd]

how long should it take for my exposure to come out under 1000 watt metal halide. screens are not coming out all the way

 

[splathead]

My guess is 6 or 7 minutes. it takes 13 with a 500w.

Only sure way is to do a test (search here for step test) where you exposure a test screen to various times to see which area washes out best.

 

[Solmu]

The chart I have here suggests about eight minutes, but obviously that's for one specific setup that is unlikely to exactly mirror yours.

 

[RichardGreaves]

Nobody can tell you how long with the information you listed.

What emulsion are you using? Solvent resistant diazo sensitized emulsion takes 5 times longer to HARDEN than plastisol style SBQ emulsions.

What is the distance of your screen to the lamp? Invisible UV energy degrades with distance.

When you are tired of guessing, purchase a Stouffer 21 Step Sensitivity Guide US$8.00 to US$12.00 depending on where you buy it. It will give you visual feedback and should be on every screen your make for the rest of your life.

http://www.t-shirtforums.com/screen-printing/t24239.html#post143704

Exposure FAQ of Screen Making Products

It is a 5.5" film positive that is opaque on one end and clear at the other, with 21 measured steps in between.

The 21 steps, simulate 21 different exposures with one exposure. You get visual feedback so you can make clear judgements about exposure without guessing.

When you develop the stencil, areas that didn’t get exposed will dissolve with water and go down the drain like the inside of the screen. You want a minimum of a Solid Step 7 that survives and holds in the mesh. More exposure will make your stencil more durable and less will make the stencil less durable