|
To elaborate, by definition and by use, linseed oil is, and has been considered a "varnish" since its use began. The purpose of a volatile thinner (MS) is literally to "reduce" the amount of material appied, so your 50/50 solution applied by way of "oiling out" is sound reasoning and practise as relates to applying less of the "varnish" material.
The intent of "oiling out" as I understand the process is not to saturate an absorbent layer with whatever amount of oil it might take on, but to appy the oil as as top-coat "varnish". Cut 50/50 with MS , it's most likely the "dry" passage will absorb the solution through and through, even into underpainting layers unless a barrier layer prevents this.
Oil is applied very sparingly to the surface (to be sure, one doesn't flood the surface nor apply it with a brush). A wee bit applied with the fingertips and massaged into a dry surface with the heel of the palm using enough friction to warm the oil and the painting, keeps oil on the surface and it's possible to apply even less sum total in this fashion than would result from applying a reduced mixture. Oiling out is one of those processes that's best demonstrated, it's difficult to explain in text.
The rationale for keeping an oil layer nearest the surface rather than permeating the paint layers is rooted in the "fat over lean" principle as it's understood for a layered approach to painting. Oil rich layers are found to yellow and darken over time, but a linseed oil film of itself will not necessarily yellow or darken unless subjected to extreme damp and darkness. Ambient daylight where paintings are hung for display is enough to keep paintings from darkening or yellowing.
|