Testing Canvas Coatings

[hdomke]

Do you know of any standardized ways to test canvas coatings?
My clients frequently ask me: How safe is that canvas print in a busy hospital?

I couldn't find much on the subject so I came up with my own "stress test" to evaluate resistance to various kinds of trauma.

On Friday I performed these tests on some canvas prints from my Epson 11880. The coating used was ClearShield® Type C Satin applied as 4 thin coats with a HVLP sprayer.
1. I wiped them hard with a solution of 50% dishwashing liquid and water.
2. I wiped them hard with Windex.
3. I wiped them hard with undiluted Hydrogen Peroxide (3%).
4. I wiped them hard with Chlorox Soft Scrub which contains abrasives.
5. I dragged the tines of a fork across it with pressure up to 15-pounds.

The above tests caused no harm to the prints with only two exception:
1. Extensive scrubbing with Chlorox Soft Scrub eventually made the print start to rub away.
2. Very high pressure with the fork did cause scratch marks if I held the fork at the right angle.

Feedback, suggestions or links to other forms of testing would be appreciated.
Henry

[bill t.]

I arrived at my present standard of three thin but very even coats by these criteria.

1.  I can spray a blast of Windex directly on the print and let it dry, with no apparent damage after a few days.

2. Wiping hard with a cotton towel wet with water does not harm the print.  It is especially important to pay attention to the peaks of the canvas texture when doing this.

To get adequate protection from only 3 coats it is very important to use meticulous technique, otherwise some areas could be under coated.

FWIW, three coats is the maximum amount of coating the does not adversly affect the color gamut of the print.  Up to three coats, the gamut volume usually increases by extending lower L values downward, without much diminishing the highest L values.  But coating beyond that starts to push down the highest L values.  This is based on tests with Glamour II and Epson Exhibition Canvas Gloss.  The results from matte canvases will be similar.  Save those target prints, read them both before and after coating.

Also FWIW it should be noted that all the "no coatings needed" canvases I have tested to date bleach to the white substrate within a few seconds after being sprayed with Windex.  At public venues like hospitals, hotels, etc, it is almost certain that Windex or 409 or something like it is going to reach your canvas surface sooner than later, if only as collateral damage from cleaning the windows, wall, or headboard.