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Q&A: Foiling Over UV Coatings

This Q&A exchange was extracted from the Foil & Specialty Effects Association HelpLinks forum, an online resource whereby FSEA members can ask questions about challenging projects or conduct research on machinery or supplies and receive advice from the online FSEA community.

Question:

We recently came across a "problem project" involving the cover of a perfect bound book. The outside was flood UV coated with "stampable" Gloss UV (this term was used by the printer's coating supplier). The inside was flooded with a "standard" Gloss UV. It was printed on a 100lb matte cover stock. We were stamping on a Brause SBL 1050SEF and the foil required was a shiny silver. After much trial and error, through varying brands and suppliers, we determined Infinity MX10 as running the best – using copper dies at 260 degrees. Foil stamping was on the outside only, but we still had issues.

Even if we pulled very small lifts (1/2") out of the delivery, the foil appeared to be picking onto the inside of the cover above it in the lift (just like ink would offset). The surface of the foiled image also looked like it had very fine pitting – perhaps dust on the sheet?

I was wondering if you had any words of wisdom for foiling over UV coatings (or UV-cured inks)? Would Dyne testing pens be a good investment?

Answers:

1. The UV coating has to be imprintable. It must contain no silicones or certain waxes in order to attain proper adhesion.

2. Can the foil stamping be done before the UV coating is applied? If you're using a regular gloss or silver foil, generally the foil can be UV coated over the top of the foil. It would be difficult for anyone to identify that it has been coated over.

3. You can use a permanent marker to test the Dyne level of the sheet surface. It is a "poor man's" dyne pen, but it gives basically the same results. If the ink beads up you are going to have trouble. The dyne pens have a limited shelf life, but we always have permanent markers around.

4. We only have two print customers where we will entertain foiling over press-UV. We did extensive testing with both customers to ensure a happy foiling experience for all. Even doing that, we are still cautiously dipping our toes into UV coatings. So far, we have not had an issue, but we work very closely with these folks to maintain consistency in the chemistry.

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