Chroma Blue Emulsion

[Michelle]

Is anyone using Chroma Blue emulsion with unfiltered uv black lights. I am using 6 40w uv unfiltered black lights. Coating 110 mesh 2/1 and CAN NOT dial in my burn time. I am using a wedge. I can get part of the image to wash out between 5 and 6 minutes but it takes forever and I think I am more just blowing it out. Should I be coating only 1/1? And just start all over again? My unit is diy. The box is completely sealed off and I am using foam for pressure instead of a vacuum. I am always under or over....no in between.

[Catspit Productions]

Now I have never used the emulsion you are using. At least that I can recall but the first question I would ask is; are your film positives 100% opaque? The reason I ask is you have a long burn time for some reason. I do a 1/1 coat and I use a multiple bulb industrial black lamp exposure unit too. I don’t think a 2/1 coating method will affect things all that much but you could try a 1/1. My exposure times are between 30 and 40 seconds on a 125 or 110 mesh with a photopolymer emulsion.

So with a 5 minute burn time it is completely possible that you are semi curing the emulsion if the film positives are not dense enough to block all the exposure light. I’m pretty sure Chroma Blue is a photopolymer emulsion so it should be relatively fast compared to a dual cure which might have an exposure time of a few minutes. A photopolymer should be faster than that and burn in under a minute or so I would think.

It’s hard for me to say what is going on there but I would also ask how old is the emulsion? If it is older than 24 months then it may be very slow and too old to work well enough to get a good burn.

Check into those factors and let us know. Maybe if we know that we could guess at this further...

[Michelle]

Jonathan, I think I love you! lol. I looked at my film on my light table....streaks! That would be the culprit. I have a 1/1 screen ready to go and am going to double up the film for now. I have an Epson Stylus Pro 4880 with Fast Rip that I have no idea how to use...YET, so for now am just using my regular inkjet printer on the darkest setting. I will let you know how it goes.

[Leadfoot]

Mchelle,

That was one of my issues starting out as well. I believe I was using that same emulsion you are using before I swithced to a dry stencil system. It is a great emulsion and easy to expose. A 2/1 coating should not affect the image burning at all. If you don't have a Stouffer step test I highly recommend one and use it on every screen that way you can keep track of your times accurately. Good Luck and be sure to post any questions on here, Jonathan and others can likely help you out.

[Catspit Productions]

That's great Michelle,

If you want to output inkjet film without RIP software you should check out this blog post:

http://howtoscreenprintshirts.com/2011/ ... -software/

The tips and advice in that blog post will help you get the darkest inkjet film positives possible without using RIP software. It is recommended that you use a decent quality inkjet film and use water proof film if at all possible.

You can double up film when necessary and practical. Obviously halftones or very fine detailed work may not burn well with doubled up film positives but with simple spot colors and minimal detail it will work just fine.

A step test is a good idea. Leadfoot is correct in that it may help you dial in the correct exposure easily. Saati sells them and you can use the Catspit code for a discount if you like:

http://store-d0bac.mybigcommerce.com/pr ... Guide.html

Just put in code catspit at checkout and you'll get 5% off list pricing plus free shipping.

Good luck and we look forward to hearing about your results. Thanks for posting!