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Originally Posted by FarmerLarry |  | | | | | | | | | what the pro and cons of either liquid or film emulsion? | |  | |  | |
In the circuit world, I would guess you used indirect stencil films that are processed first, then adhered to the mesh. In this forum it's usually plastisol on t-shirts.
If you're using waterbased ink, you may need the durability of a direct emulsion. 100 prints - not so much.
Vacuum Frame
Direct stencils require a vacuum frame that can hold your entire screen frame compared to indirect stencils that just have to hold a positive and the stencil film.
Labor costs
Direct emulsion stencil is the most flexible, most durable, most chemical and mechanical resistant method of stenciling but
is very labor intensive. The final stencil formed contains 25% to 40% per cent solids. To make a smooth, gasket like film stencil on the bottom of the mesh, multiple coats of the emulsion must be coated.
Direct film is more costly as a raw material, but because you only handle it once and it forms a perfect stencil in seconds, it can be more economical in the long run.
Water is poured on the mesh and surface tension holds it there for a while. The film is rolled on to the wet mesh and it absorbs the water with capillary action. It becomes soft and sticks to the mesh. Because there is very little evaporation required compared to 60% to 70% in direct emulsion, it dries very quickly and does not take on the rough texture of the mesh, as the coating shrinks, as the water evaporates. No coating troughs or bucket lips to clean.
You'll have no trouble deciding how to spend your time
You're starting out again. Do you have more time - or money? If you need to maximize your time - use direct film. If you are retired with an income - on your farm and you want to make some quick signs & t-shirts for your wife - use direct film. Ask any screen printer why they use direct emulsion and it will be because they need ink or solvent resistance & durability for their print runs of more than 10,000 or because they don't require the best stencils for rough surface textiles. Or because it is cheaper to buy and they don't count up the time they spend "saving money" using direct emulsion.
The debate over Capillary Film vs. Direct emulsion will be going on long after I'm dead, but there are clear facts that can help you to make your choice.
1. Capillary film dries faster because the water in the mesh that is absorbed with capillary action is all that has to evaporate, not the 65% water content of the average emulsion.
2. If a screen coated 1x1 works for you and you are satisfied and it gets the job done, I see no reason to invest more money for direct film. If an old pickup truck works for you, stick to your guns, but if you need to go faster or carry more load, you will need to upgrade or you can't compete.
3. Both are good on the rack, in a light safe room for about 30 days. Yes, capillary film dries faster, but it still dries all by itself. All arguments about drying time between film & emulsion are eliminated if you coat your screens at 1 day before you need them. If you wait to the last minute, you have other problems. You can't tell the difference in a 1 day or 1 week dried screen. Have either one on a rack, ready-to-expose. No waiting.
4. If you want a specific Emulsion Over Mesh (EOM) thickness. If you want a smooth gasket for printing the best half-tones - capillary film is more reliable - coated plus or minus 1 micron.
5. If I were magically transported to your shop, I couldn't make a better screen with multiple face coats than 5 year old Jennifer making her third screen with direct film because of the effect evaporation has on the stencil surface & thickness.
6. I hate cleaning the emulsion coater.
I promote the philosophy that it is more important to make money
printing, than
save money in the screen room. You will never make a good living for yourself focusing on how well you saved money in the screen room (it helps to pay attention of course). You make money selling printed shirts. Selling, not printing.
Ask yourself every minute - Does it help you
sell shirts? Does it help you print faster?
Whats better, liquid emulsion or Film 
