I've done plenty of overlays using the transparency film and self-adhesive laminating sheet method but was never happy with its finish or colorization. There were always very tiny bubble which could not be removed. The coloration was also very week compared to screen printing especially evident with colors like yellow.
Heat-applied laminating pockets provide a much better finish but can cause clouding or warping not to mention that the edges require an overlap so it will not separate. The coloration is still not on par with screen printing.
Having worked with multiple transparency films for the special silver bordered Protector overlays and needed a way to join the layers together, I decided to try fusing the layer together with a soldering iron.
I print 2 layers standard and 2 layers in reverse, then put printed sides together so as to protect them. I then paint the white layer in between the second and third layer with the final step being that I fuse all 4 layers together with a soldering iron.
The colorization is fantastic, even with yellow. This is the closest to screen printed colorization as I've seen from a DIY overlay. No clouding, no warping, thickness close to original and rigid like the originals.
I fuse the sheets together around the entire outside edge. This is after I trim the edge. It helps to align the layers by using a clamping device then soldering a hole directly through all the layers in a portion that will not be used. I then work a side at a time. Proper trimming and careful soldering will make a difference in how good a quality the final product is.
As a note, I used a reverse image so that the printed side would be trapped on the inside and would be protected from scratches or moisture.
For some reason, I had trouble locating the same inkjet transparency film that I was originally using. It was 4 mil thick, crystal clear and was made for both Inkjet and Laser printers (not copiers). I however did find a cross reference on Precision's website for item 10-405. 3M CG3460, CG3480, Arkwright 345-25-01, and HP C3834A were listed as the similar products. precisionimageinc.com/crossreferenceguide.html
I tried a few different types which were not suitable. Film made for copiers was not only too think but also could not absorb the ink. I also tried Waterproof Screen printing film, however it was not completely clear.
Last Edit: Sept 16, 2015 18:12:56 GMT -5 by 50tbrd
If someone was to use Laserprint, get transparency film specifically for laser printers. I've only used film which has one rough side for inkjet and one smooth side for laser. This means that the laser print side is used to protect the other side from moisture and create a smooth finished glossy outside. Do not use this kind of film for Laserprint as you'll be left with a rough side on the non printed surface.