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MITRA Forum Question Details

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  • Sealing the back of canvasesApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    Question asked 2017-03-15 06:53:44 ... Most recent comment 2018-09-22 06:07:50
    Flexible Supports Grounds / Priming

    ​I've come across conflicting information on this.

    Some old manuals advise us to seal the canvases also from the back to protect them from humidity. Japan size and tin foil were highly recommended to do so.

    On the other hand, I've read that canvases sealed from behind perform worse than canvases where the linen fibers were left to breathe. 

    What is your opinion on this topic?

    Cheers. Nelson

Answers and Comments

  • EditDeleteModerator Answer

    This practice is almost uniformly condemned today. It is less of an issue of the fibers needing to breath. The more important reasons are twofold. The application of materials to the reverse of the canvas can create brittleness in the case of Japan size. This may also rot the canvas overtime.

    Additionally, whenever you adhere something to a portion, as opposed to the complete, verso of the canvas you will eventually see that impression of that material telegraph through to the surface resulting in a topographical bulge in the shape of the applique that can be seen on the front of the painting. You have probably seen patch shaped bulges visible on the surface of poorly restored paintings. I have also seen this happen with gallery labels that were stuck on the backs of exhibited paintings. This is all just the result of the inevitable natural alignment of physical forces that occur when a smaller objects is attached to a larger and flexible object. The same does not happen with lined paintings but that has its own issues.

    The tinfoil idea would not be terrible as long as no adhesive was used. Today, we generally just attach a rigid, vented backing board (eg Fomecore or acid free blueboard) to the reverse of the stretcher. This does almost everything positive that the earlier procedures did without any of the negatives. BTW the small vents left in the backingboard prevent the creation of a micro-environment which may occur in very humid environments.

    Brian Baade
    2017-03-15 16:46:08
  • EditDeleteModerator Answer

    ​If you are interested in learning more about how to prepare your own backing board, instructions can be found in our Resources section in the "Storage, Exhibition, and Handling Tips" document.

    Kristin deGhetaldi
    2017-03-15 16:55:03
  • ApproveRejectUn-ApproveUser Comment

    ​This is great, thanks so much!

    I just came across this wonderful article and I was wondering if the homemade version of Marvelseal is also advisable for canvases (linen, hemp or cotton duck) or just wood?

    Would it also make sense to apply this plastic/aluminium backing to thick watercolour paper before framing it, to prevent potential contamination from the backings used in most commercial frames?

    2018-09-22 06:07:50

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