Funny how things happen sometimes: Just when I needed it, I was given two long and narrow screens that are just perfect for a printing job I just completed the artwork for. But of course, the screens are way too long to use with my exposure table. I'll use Mr. Sun to burn the screens. I don't have a glass long enough to hold the film positive onto the screen either. Somewhere I read or heard someone say that a person could use spray adhesive to stick the positive to the screen. Is this an option or is there a better way? I do not want to go buy a long piece of glass for this if I don't have to. Hank
spray adhesive works but it gets all over, and if it is fine detail, sometimes doesn't stick down perfectly, or if a big area of black, it heats in the sun and puffs off...that said, it can be done. Don't roll the posi after, you'll never unroll it.
The better option is to use Andymac's technology, but if you can't....
I tried the vacuum bag exposure technique with a halogen and ended up going back to compression because the bag lost some of the vacuum...but in a pinch, when using the sun, I think it would work fine because even if the vacuum was lost over a few minutes the exposure would be so quick it wouldn't matter. But the bags might be too small.
You could also get a large piece of glass and just press it down with weights at the edges while under the sun. Then you could block off the middle and expose where the weights were if you don't want unexposed emulsion at the sides.
Mineral Turpentine. Use a squeeze bottle and tip enough onto the screen, then lay your posi over, then squeegee the excess turpentine out from underneath the posi. I've used this method for.. well a long long time, and not just for large (3000X1000mm) posi's, but right down to A4 size, solids/halftone's it doesn't matter. You get perfect contact with the mesh - I can expose 85LPI halftones using this method. If your posi is flat you won't have to worry about anything, if the edges are curly you'll have to keep an eye on it and give it a lick to the edges with the squeegee while it's exposing - I've only ever found that an inconvenience when using comp-cut vinyl with a clear backing sheet for film.
If you're using inkjet posi you'll notice that the posi will be clouded or a bit opaque when you pull it from the screen and the turps starts to evaporate, don't freak out, the cloudiness/opacity will disappear once the posi is fully dry. Just set it aside and have a look at it in an hour.
Andy: thanks for the offer. If I cannot get a good burn with the suggestions above, I may just take you up on the invite.
The others: thank you for your time and thoughts. (The three best things about this website: 1) the poster images, 2) humour (with an edge!), and 3) willingness of people to help others. Many thanks to all.)