MITRA Forum Question Details

Hello Carson,

You raise a few good things to discuss. My answer won't be sufficient in itself, I'll also look forward to reading what others say.

First is yes, it's best to give a good quality sizing and gesso, first to prevent wood tanins and colourful molecules from migrating into your paint, and too much of your paint to sip into the wood, chemically rotting it.

Protection against warping and (mould)-rotting is best assured from earlier proper drying and treatment (in low/high pressure chambers). Your sizing and gesso won't prevent much warping and rotting that would come from the back side of the wood exposed to too much humidity. This is also true for textiles.

One issue with hardware stores products is they are more wild than artist products. You might find good materials but are also more likely to be disappointed in ten years when things go wrong. They don't need to have the quality artist brands put into it and are less likely to be able to support you and conservators when troubles arise.

Sealing with them, you have arguably more risks to get bad migrations into the paint and delamination over time. Hard to say unfortunately, it's a gamble.

Gac100 is surely a good product with fair competition I'm confident. You might want to try other big brands see if you get more bang for your buck. Do avoid mixing two brands however, since it's hard for one company to support when you use products of two (or more) different companies.

They don't list the raw materials on the label because US/EU laws don't enforce the requirement (yet) to write down the INCI ingredient, like in food or cosmetics products. That might come some day... 

And you're likely to still be disappointed. Because INCI wise, the spectrum of 'Acrylate Copolymer / carbomer' is infinite. So it's not to hide that it's bad, it's just that it won't tell you much anyway about the quality. Their INCI list would be something like: 'Water, Carbomer, Carbomer, Carbomer, glycerine, sodium hydroxide, benzoisothiazolinone'

I'd trust and stick with one of either Daler-Rowney, Golden, Lefranc et bourgeois, Liquitex, Royal Talens, Winsor & Newton, for the choice of long-term reliable polymers in their acrylic primers. Not DIY stores. But I don't know which is most cost effective among them.

The isolation coat is an arguably good trend, to my understanding:

Plus side is, it's far safer to replace the top (final) varnish since you won't damage the pictural layer.

Con side is, it's far harder to repair the pictural layer if something goes wrong in it (or goes in from behind because the primer was poor quality).

You don't need to dilute it, it's just a first varnish that doesn't dissolve in the same solvent as the top one (and keeps enough flexibility of course). I think Golden and Liquitex offer the two kinds. I don't know for the other brands.

I wish you a nice day,

Lussh