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MITRA Forum Question Details

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  • Backing larger canvasesApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    Question asked 2017-10-01 21:45:08 ... Most recent comment 2017-10-05 19:49:39
    Flexible Supports
    My paintings tend to be larger (7',8',9') and can be quite fragile. To help protect them, I have typically stretched the unprimed canvas over a cradled wood panel. My first question is whether or not this is actually beneficial, or whether the panel is unnecessary? The canvas rests over the wooden panel but is not glued down.

    Recently I've been considering going back to stretcher bars (probably aluminum) and inserting a lightweight foam into the stretchers attached only to the cross bars, so the perimeter could still be stretched if necessary. My second question is whether or not this is a more permanent solution?

    I do not have access to gator board, because I can't  find single sheets and the shipping is outrageously pricey. I do have access to foam core and 1/2" and 1" sturdy construction insulation foam (which seems more rigid and doesn't have a paper veneer).  My third question is whether foam core or the construction foam is worth using/and or dangerous in terms of off gassing etc. to the back of the canvas? 

    My fourth question would be if you all have any better solution/suggestions I hadn't considered.


Answers and Comments

  • EditDeleteModerator Answer

    ​There is nothing wrong with the first scenario that you have proposed so long as the wooden support is of decent quality (and therefore is not prone to splitting/cracking and/or lots of movement...). 
    As for the second....this is a very good question and we are happy to have this recorded on the forum. I am including a screenshot of an excerpt from The Conservation of Easel Paintings (ed. by Joyce Hill Stoner and Rebecca Rushfield) from an excellent chapter written by conservators Carolyn Tomkiewicz, Mikkel Scharff, and Rustin Levenson. We would not advise using something like construction foam for the very reasons that you have already cited. But certainly something like polyester batting can be easily obtained and is very lightweight. These images will also help to give you an idea as to how conservators construct padded backing boards. Let us know if you have additional questions.PaddedBackingBoards copy.jpg

    Kristin deGhetaldi
    2017-10-02 12:07:53
  • ApproveRejectUn-ApproveUser Comment

    Wow, that's such a great idea, thanks! How would I go about securing the coroplast to the aluminum or wood stretcher so it could still be removed?

    I know some artists who simply place foam core in the stretcher bars and stretch canvas over the top. What are your thoughts on this? 

    2017-10-02 14:17:12
  • ApproveRejectUn-ApproveUser Comment

    Sorry, I just saw the answer to the first question.

    2017-10-02 14:40:56
  • EditDeleteModerator Answer

    ​​I would think that screws made for metal and finishing washers would work just like it does for wooden stretchers. As for placing foamcore inside the stretcher bars and then covering with additional canvas...I am not really sure I see the need for the additional canvas except if you want to provide some sort of buffering layer for a vented backing board. The padded backing board should be fine in this instance. You could also do something called a "cami-lining" but that might be overkill at this stage depending on the materials and technique you use but it is certainly an option. See the attached photo from the same chapter cited above.CamiLining.png

    Kristin deGhetaldi
    2017-10-02 16:10:51
  • ApproveRejectUn-ApproveUser Comment

    Sorry, I don't think I was clear. I meant that prior to painting, an artist will cut foam core to size and lay it into the stretcher bars from the front, as a kind of partially floating panel insert. Maybe it's attached to the cross bars only. Then they will stretch canvas over the top and the canvas rests on the foam core or close to it. Then they paint. I know people who do this with gatorboard as well (maybe coroplast could work too?).

    2017-10-02 17:21:49
  • EditDeleteModerator Answer

    That should work as long as it is secured to the stretchers in some manner and not exerting pressure on the canvas. FomeCore does become more brittle over time. This is not really an issue for backing boards but it may be best to not have it in contact with the canvas. A quality Gatorboard or the like would probably be better. I am not sure that Coroplast is the perfect choice as, if I am remembering it correctly, there is has a corrugated construction that is evident in the surface topography.

    I have even adhered hardboard to the front of a strainer (it is called a strainer if it is not keyable). This is very similar in concept to the panel-back strainers used by some early 16th-century Italian and Spanish oil painters as well as the panel back stretchers (keyable, despite the incorporated panel) used by some Pre-Raphaelites and Hudson River School Painters in the 19th century. This practice has been determined to be very beneficial.

    The size of your works would probably preclude the use of heavy materials like hardboard but a lighter weight material like Gatorboard may be a good idea.

    Brian Baade
    2017-10-03 17:36:23
  • ApproveRejectUn-ApproveUser Comment

    Yeah, thanks. I think the ideal situation would be a keyable panel stretcher or something like it.

    So even though strainers are not ideal, a rigid panel strainer or a cradled panel with canvas stretched over (I'm guessing they amount to the effect) generally ages better than a painting on a keyable stretcher?  

    My paintings can get heavy with layers and sag a bit in the middle so I thought not being able to key out might be an issue down the road. It would be relief if you said otherwise.

    Would it be more beneficial to adhere the canvas to the panel?

    2017-10-03 19:51:35
  • EditDeleteModerator Answer

    Yes, the panel back strainer is generally preferable except in areas in regions with very high and unrestrained humidity where there is the possibility of mold growth. The panel helps to keep the canvas in plane, searves as a buffer against rapid changes in the environment and protects the painting from impact form the back and even to a certain extent from the front. A keyable panel back stretcher is even better, but requires much more refined woodworking skills

    Brian Baade
    2017-10-04 13:09:28
  • ApproveRejectUn-ApproveUser Comment

    ​Thanks, that clears up a lot. I'll stick with the panels for now.

    However, I did read this the other day. If you have time I'd be interested in what you think/if you've seen this done before. Under section D, there's a design for a cost effective variation on panel back stretchers that artists/conservators could easily make. I think for my purposes, it might be possible to do it with 1/4" plywood and a small addition to the design.

    2017-10-05 10:50:06
  • EditDeleteModerator Answer

    ​It has been a few years sinse I read all the way through that section. That modification looks really great. Go with it.

    Brian Baade
    2017-10-05 19:49:39

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