RE-VARNISHING a mixed-media oil painting
this is my personal experience. follow the Manufacturer Instructions for all safety and product use guidelines. process pics of painting inside this post
***update 2023: my current solution is to apply Gamvar Matte over the piece. this will not give a true flat matte finish; more of a satin/semi-gloss since my painting mediums are usually gloss finish. i apply a thin layer with a soft brush. i do not pour varnish over canvas. note that for re-varnishing, the painting would already have Gamvar Gloss or Satin, so i'm not mixing different brands.
for my last batch of new pieces that needed to be varnished, if the canvas surface was not already evenly glossy from the paint and mediums, i used Gamvar Matte for the entire varnish process to avoid any removal and re-varnishing. i'm not a fan of the cold wax varnish process. mixed media on stretched canvas can be tricky to varnish based on your process, materials used, how well you seal the surface, and at what point you fully prime (start) or seal the canvas (mid to end process). good luck! :)
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original post: March 2021
painted on a custom made 14" heavyweight cotton canvas, with at least 2 coats of quality gesso. mixed media technique with inks, marker, acrylic, and oil with fast dry painting mediums.
i decided to use this painting to see if i could get the surface up to a even finish. i think i varnished with Gamblin Gamvar Gloss maybe 1-3 months after i finished it. i realize that's a big span of time that could effect all of the below. the original painting was fully touch-dry but i did not wait 6 months to varnish the first time.
the canvas was very porous with gesso to start. the finish was more like satin, spotty up close. it hung in a gallery for 6 months. so now it’s been 15 months since i finished the original painting. although this experiment was enjoyable for me, it’s not something i want to do for every painting. in the future i'm going to revisit a better preparation of the canvas, or oiling out before varnish, and/or varnishing with a buffed cold wax. also oiling out is common for traditional oil painters too, not just specific to mixed media.
first i removed the varnish with Gamblin Gamsol and a soft cloth. i wasn't sure what brand of varnish i used, so i figured to start with as clean of slate as possible. since the surface was already spotty, there wasn't a clean indication of where the varnish was removed or not. but with each step in this process, the surface evened out more and more.
next i did the "oil out" process with 50/50 Galkyd Gel/Gamsol. perhaps the regular formula of Galkyd would have worked better, but i didn't have any at the time. i brushed on this mixture and the painting was really shiny. as it dried it was less shiny, but the overall surface quality improved. when i was rubbing off the excess mixture i noticed that some paint was coming off on my cloth, but it wasn't enough for me to be concerned about. it also could have been from the edges of the canvas. i just wiped the excess off more gently.
soon after (same day) i applied retouch varnish spray (don't ask, my idea). again the painting surface would improve bit by bit. After 24 hours of applying the retouch varnish, the surface was sticky. i used Gamsol and a soft cloth to rub over the surface, but i was not taking off a lot of product or paint. maybe i could have skipped this step, but it didn't cause any problems with the finish, just a longer dry time.
it took 3 more days but the painting surface was dry again. if at some point prior to this the surface would have stayed really shiny and even, i probably would have just re-varnished with a gloss or damar. but i decided to finish with a Gamblin Cold Wax application with a clean soft cloth. after the first thin layer i opted for a second coat of wax. I’m going to buff it the next day and see what happens.
after about 24 hours i buffed the cold wav with a foam buffing pad. actually 2 different foam textures and my rag, but all very smooth. it wasn't a dramatic transformation on the shine since i was going for satin as the max option for wax. i'm also going to finish with Tight'N'Up spray on the back side of the canvas. when i was buffing i used my hand to firm the back of the canvas while i buffed. it was already initially stretched really tight and made with a heavyweight cotton.
it was a lot of hand/arm work, and this was just a 14" canvas. overall a 5-day re-varnish process for this small-size. but if the end goal was to even the surface, yes i did that! still don't think i want to do it again. might have to double the price for extra labor; kind of joking.
ya'll keep painting, keep practicing! ~t.
(update: August 2021)
ps - before i posted this, i've also experimented with another oil-out method. no varnish was applied until the very end, as normal. this piece was 12x16" on a Fredrix Mixed Media Canvas Board (mixed media Oil Painting, the moth image on the main news feed). some of my dark areas dried matte. i did a oil-out with Gamsol and Gamblin's solvent free fluid. again, don't ask... i just try things if i can't find any good data telling me otherwise. i did a 50/50 mix and wow did it gloss up the piece! i wonder how this will work on a stretched canvas. anyway... the 50/50 was way too much solvent-free fluid and it was taking forever to dry. with a big soft brush, i started brushing off the excess that was just sitting on top of the artwork, and letting oxidation do the rest. i did this for a few days in a row. when it finally dried, i rubbed a soft cloth with some Gamsol across the surface to make sure it wasn't sticky. then i did a final varnish with Gamvar gloss.
***SEE 2023 update at the top of this page.
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