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MITRA Forum Question Details

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  • Diluting retouch varnishApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    Question asked 2019-11-25 17:42:53 ... Most recent comment 2020-01-11 22:50:11
    Varnishes
    Question

    ​Hello,

    Can retouch varnish be diluted to make it less shiny, and if so, with what?

    Thank you!

Answers and Comments

  • EditDeleteModerator Answer

    Which solvent to use depends on the brand and what the carrier solvent is. Retouch damar can be diluted with pure gum spirits of turpentine. Some synthetic retouch can be thinned with odorless mineral spirits.  That said, most factory-prepared retouch is intended for use at package strength and may not unify surface sheen to a satisfactory appearance if further reduced. Also, because retouch is generally applied to pictures that are still drying, it's essential to verify that the paint film is not at all soluble before applying any top-coat, especially one diluted with a strong solvent.

    Matthew Kinsey, Utrecht Art Supplies
    2019-11-25 18:29:58
  • ApproveRejectUn-ApproveUser Comment

    Thank you, Matthew! 

    I am currently experimenting with Windsor & Newton Retouch Varnish as a final varnish. I'm interested in using retouch varnish because I can't wait for months to apply varnish. (Is W&N Retouch Varnish made with Laropal? Throughout my research, I find it difficult to figure out what various varnishes are made of. Is there a chart somewhere?) I've heard that this product can be thinned with OMS and would love some feedback on this. Are there any reasons not to do this? Will doing so create a less shiny varnish? Is it okay to dissolve Cosmoloid wax in the solution (warmed in a sealed glass container of course), in order to make the retouch even more matte?

    I read your previous answer to someone's question about applying a final varnish over retouch varnish. Is there a final mat varnish that is appropriate to apply over a coat of pure (not diluted with OMS or supplemented with wax) Windsor & Newton Retouch Varnish that would have a matting effect? If so, what product do you recommend?

    Finally, I've read MITRA's Resources pdf on varnishes and took note of the final bullet point: "If your surface is proving to be particularly stubborn once your composition has been completed, it is possible to achieve an even level of gloss by applying alternating coatings of HMW resins (Paraloid B72, MSA varnish, etc.) followed by a LMW resin (Regalrez/Gamvar)". Are there further resources that go into detail about this layering approach that would be helpful to a painter?

    My goal is to exhibit recently finished paintings with unified matte surfaces and take reasonable archival precautions withough going so crazy it limits me creatively. 

    Thank you again!

    2020-01-11 15:05:20
  • EditDeleteModerator Answer

    ​Keep in mind that I am a studio artist, not a conservation expert, and I didn't participate in creating the MITRA resources documents. I can tell you from experiece that it's a lot easier to control surface sheen by applying matte varnish over gloss than the other way around. It's probably unlikely that W&N will disclose what specific resins are used in their varnish, so you should probably plan to test a few products, with focus on ones that use the same carrier solvent. I don't see any problem with adding a cold wax matting agent to retouch varnish, but layering on top of such a mixture could be problematic, if you plan on top-coating with a final varnish layer. Also, remember that while picture varnish can be considered by the artist as an integral part of the final pictorial effect, there's a chance that your original varnish might be removed, and your desired matte finish lost with it. Many artists just use matte varnish to solve tricky lighting issues and would not necessarily care if a gloss top coat were later used, but it sounds like you really want these pictures to be viewed with a matte finish. It seems to me that it would be a good idea to document this preference in some way, for the benefit of collectors.

    Matthew Kinsey, Utrecht Art Supplies
    2020-01-11 20:55:20
  • EditDeleteModerator Answer

    This is a big subject, but what you mention is true. However, this procedure works best when the high molecular weight coating (or even a similarly MW, gloss coating) is not soluble in the same solvents as the upper-most varnish. For instance, apply a xylene soluble b-72 varnish and then apply a regal-rez or other less polar varnish on top of that layer. The 2nd coating can be a matte or satin varnish. The essence here is that the topmost varnish does not overly bite into the preliminary, or saturating varnish. If you have the capability of spray application, the necessity of differing solubilities is greatly lessened.

    Brian Baade
    2020-01-11 22:50:11

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