A reader said he tried sun-thickened oil on my recommendation but it didn’t demonstrate the handling quality that I’d claimed for it.
Sun-thickened oil has the happy quality of maintaining body even when thinned, or so I claimed. My correspondent said his paint was rather more transparent than usual; he’d expected the opposite.
First, as with any art supplies, ensure that you actually have what you think you have. Manufacturers can claim anything they want about their products: ‘flake white hue’ without any flake white; ‘copal varnish’ without any copal. I can pile up the examples.
Second, if you actually have what you believe you have, make sure to use it appropriately. This statement is open ended, I know, but in this instance, my reader bought a medium that DID contain sun-thickened oil, but it was mixed with Venice turpentine. Venice turpentine–a thick balsam–imparts transparency to paint.
Mixing these two ingredients together can cancel or diminish the good effect of both, which is most-likely what happened in this case. I use both ingredients– but not together. I sometimes add sun-thickened oil to the lights for extra body, and I sometimes add flavored turpentine (10:1 or 12:1 turpentine to balsam) to my darks. Lights need