Turner Retouching Varnish
Use this light, fast-drying mineral spirit-based varnish to restore original brilliance and luminosity to colors that have dulled or sunken in, on unfinished works. Or use it as a temporary varnish to protect the canvas from dust or during early transport. Since it has a very diluted base, it does not suffocate the painting and does not slow down the oxidation process very much. Reduces in strength over time.
...
Sennelier Artist Sprays
Turner Retouching Varnish
The varnishes allow you to protect a work from natural and chemical attacks. They give the painting a uniform matte, satin or gloss appearance. Varnishes are preliminary varnishes (touch-up varnishes) or final varnishes to preserve the work. The choice of varnish depends on the nature of the work, the desired effect and the speed of drying. Apply to a work which is completely dry; this means waiting one year before applying the final varnish.
This application of the final varnish must take place in 2 stages: firstly, an application of a first coat of varnish diluted to 10-20%, then after drying for a day or two, of a second coat of varnish which is undiluted or diluted to 10%. Spread the varnish well by brushing in each direction when applying.This is used as a temporary varnish to protect the canvas from dust or during early transport. Since it has a very diluted base, it does not suffocate the painting and does not slow down the oxidation process very much. Reduces in strength over time.