Saturday, December 4, 2010

Tip Sheet #7 - Eco Print Shield Solutions

How to Avoid Clotting When Storing Eco Print Shield

How soon we forget, eh?

I was reminded of that this evening when I prepared to coat a 40 X 20 inch (101.6 X 50.8 cm) giclée printed on Epson® Enhanced Matte fine arts paper with Premier Art® Eco Print Shield (gloss) liquid laminate.

The coating area should be well lit and well ventilated.
If the application is by roller, masks needn't be worn.
As I poured the Print Shield solution into the roller tray a flash of white caught my eye, then another and another... it was as if there were little soft white jelly fish in the mixture. Aha... clotting!

Clotting is something that occurs with plastic coatings that cure instead of dry. The curing process is sometimes called 'setting up'.

Set-up is a chemical reaction not a change of 'phase'.

Water can change phase from solid to liquid to vapor to gas, as you know. That is what drying is, a phase change for water (or solvents).

Evaporation is stopped with 'stoppers' bottle caps and paint can lids. If you leave too much air in the container, you might see a 'skim' form on the top, but under it the mixture is fine if just a bit thicker. So I was able to store diluted blends of Golden® Polymer Varnish With UVLS in glass bottle for long periods of time without any problems.

Chemical reactions are different. That is when two (or more) chemicals combine with the oxygen in the air to form another substance altogether. in the case of Eco Print Shield a milky looking liquid becomes a clear plastic.

Stainless steel pot-scrubber catches 'clots' of
Premier Art® Eco Print Shield before they can mar the finish of a giclée.
Instead of forming a skin, these modern plastic coatings, called 'liquid laminates', start to set-up in the presence of air. The extent of the reaction depends on the amount of air in the jar. When the oxygen is depleted the reaction stops, usually in some amorphous mid-stage that resembles jellyfish. If they get onto the surface of the giclée they are hard to get off and harden into little (or big) lumps of various sizes... quite annoying.

If you read this blog you know that at the beginning of the summer we switched from Clear Shield to Golden® Polymer Varnish with UVLS. That had more to do with product availability than with the product itself.

We also tested Premier Art® Eco Print Shield, and found it good but there were availability problems with that as well (more on that later).

We've switched back now. Not to Clear Shield, but to Eco Print Shield. The problem is that Golden® Polymer Varnish cracks to much.

Retouching cracked varnish is something we hope to forget about
Vashon Island Imaging.
Cracks occur at the edges when stretching a canvas giclée coated with Polymer Varnish. The cracks can be retouched, and that is discussed in a previous blog. However, that just got to be too much.

Attending JVH Tech's big digital printing event last month turned out to be the proverbial 'straw that broke the camel's back'. At the exhibition I met Mark Perez of Premier Imaging Products. He had a stand just down the aisle from my own, where I was selling my book Giclée Prepress - The Art of Giclée ( Three things happened in quick succession.

1.) Aha... so Eco Print Shield is available the States now (I found it in Vancouver, BC, at Tricera Imaging originally).

2.) Oh look, they have a range of papers too... and films. Could these people be the 'Premier' in Epson's 'Premier' product range?

3.) OMG... a 40-page catalog...and I never heard of these people?

4.) I must be more of a recluse than I thought.

It's true, I rarely leave Vashon Island Imaging either really or virtually, but that is another story. Anyway... it was goodbye Golden then and there.

Despite the clotting (I should have known better) I am so happy that we are back on a flexible coating material like Premier's. The small amount more that it costs per square foot to use (not that small actually) is more than made up for in time save fixing cracks.

Clear Shield is the most flexible coating. (Premier Print Shield is a close second.)
The flexibility is what prevents cracking.
Being squeezed is a very thick sample of cured coating...
much thicker than you'd normally apply... and still, no cracking.
Oh, that the good folks at Clear Star Corp (makers of Clear Shield)
would solve their marketing problem by assigning the job to
John Harrington at JVH Tech. Clue in Clear Star.
The solution for the jellyfish annoyance has two parts:

1.) Store any liquid laminate (diluted or not) in a contain sized to avoid a lot of air. (You'll still get 'em in some form, maybe strings instead of clots.)

2.) Just before capping, hold your breath and then exhale into the bottle. Cap it quickly enough to trap most of your breath inside. Your spent breath is full of CO2 which is a heavier gas than oxygan. The CO2 settles like a layer of fog across the surface of the liquid laminate, retarding oxidation. (Hint, you can do the same with wine... unless you ate garlic or like garlic wine.)

Wrapping them tightly in plastic bags will keep your rollers ready to, well... roll.

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