: How does the ink hold up under the sun?

Most inks for inkjet printers fade from UV, but I have heard of some newer inks designed for photo printing on inkjet printers that are highly resistant to UV fading. If some are available in cartridges to fit your existing inkjet printer then the cost should be reasonable -- but if you have to buy an entire new printer just to get the benefit of these inks then second thoughts would be in order.

The different colors fade at different rates. Black is frequently the most stable, but that could vary with manufacturer and brand of ink.

The UV protection from the varnish would affect the rate of fading, slowing it down considerably, but I'm sure no one has tested these combinations (inkjet on wood, covered by varnish with UV absorbers) for any great length of time, so consider it an experiment.

PGJ