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MITRA Forum Question Details

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  • Extra Gesso on a Purchased Gessoed Canvas?ApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    Question asked 2017-09-09 22:42:34 ... Most recent comment 2017-09-18 09:57:01
    Flexible Supports Grounds / Priming Oil Paint Sizes and Adhesives
    Question

    ​The store-bought stretched heavyweight canvases that I've used before have, it turns out, no sizing underneath their three factory-applied acrylic gesso layers. I am concerned about oil paint strike-through, and wonder if two (or more) additional layers of high-quality acrylic gesso would insure the canvas durability? I've read somewhere that acrylic gesso, being formulated for absorbancy, will always remain susceptible to oil strike-through. I'd love to hear your professional thoughts on the subject. Also, would you explain materials and technique for attaching a rigid covering to protect the back of a stretched canvas? Thank you so much.

Answers and Comments
  • EditDeleteModerator Answer

    ​Great question....we do not see any problem with adding 1-2 more layers of acrylic gesso to your canvases. Keep in mind that most pre-primed acrylic canvases are heatset...so a bit different than the dispersion grounds that you are familiar with. While we do not think there will be any issues with compatability there MAY (big emphasis on may) be issues with potential efflorescence of additives between these two types of acrylic gessoes....but probably not. There are moderators on our board who are better versed than we are on whether this might be a problem you should consider down the road. Also how are you planning to apply your additional gesso layers should you choose to move forward? If you apply with a brush, odds are it might not look to great (unless you are going for a striated effect). One way to counteract this is to apply multiple layers that are heavily thinned with water. However if you are looking for a very smooth surface you can apply "neat" acrylic dispersion ground using a very wide putty knife....keep stroking with the knife until you can no longer see ridges, bubbles, etc. Yet again I am sure others with far more experience using acrylics will weigh in with more useful info (or even corrections). Finally you can find instructions on how to create a backing board for your painting in our Resources section in the document entitled "Storage, Exhibition, and Handling." Let us know if you have additional questions...

    Kristin deGhetaldi
    2017-09-09 23:35:27
  • EditDeleteModerator Answer

    ​Hi -

    In ASTM's Standard for Acrylic Dispersion Grounds (ASTM D 7733) three coats of a good quality acrylic ground (aka acrylic gesso) should be sufficient to block oil penetration. We happened to be the lead chair for the development of that standard and so became intimately involved in the testing and evaluation it was based on. And in fact the vast majority of good quality acrylic gessoes did meet that requirement, which should give you some comfort. That said, however, without actually testing your specific product, it is hard to know if it absolutely meets that standard. We will give some hints on how to test below.

    We would also point out that since three coats of a high quality acrylic gesso should block oil penetration on their own, a size is not 100% necessary. The acrylic grounds can really serve both functions. Where a size is absolutely critical and necessary is whenever an oil ground is being applied directly to to a canvas.

    Also, one question we would ask right off the bat is simply have you seen any strikethrough on any of the canvases you have done? If not, then you should have nothing to worry about. Some people get concerned that it will appear later on, but in truth if strike through happens it will be apparent during the drying process. So, if so far all looks good, I would rest easy. 

    That said, if you want to test this brand of canvas and have one to spare, there are two types of tests we would recommend. One, which is really a worse case scenario test, requires that the canvas be absolutely level, then apply three drops of linseed oil from a pipette or medicinal dropper and let that sit there and dry for a couple of weeks. During that time it should spread out and penetrate into the ground slightly - showing the ground in absorbent enough to provide good anchoring - but it should NOT penetrate through. On the other hand, it also should not stay put and dry as a raised bead where no penetration or spread is apparent. That is also a failure. 

    An alternative, and more of a real world test, would be to apply whatever is the thickest application you would conceivably do, using a slow-drying high oil content paint. Alizarin crimson is perfect for this (perhaps the one use of it that is beneficial!) or an organic red, like a quinacridone or napthol red, and let that dry and see if oil penetrates through. You can also try applying some of these colors with some additional medium or some solvent, to see if in a glaze or a wash anything penetrates. Again, if the back of the canvas stays nice and clean, then no worries.

    If after all of this you are still concerned, or if your tests show any failures, then yes - applying additional coats of a high quality acrylic gesso will help. And some artists will do that regardless simply because they like the convenience of a pre-stretched canvas but like also having control and knowledge of the specific ground they are painting on. Also, it can help standardize the feel of the surface regardless of the brand of pre-stretched canvas you use.

    Hope the above is helpful. And to summarize, three coats of a good quality acrylic gesso should block any oil penetration and in the testing for the ASTM Standard most good quality ones had no problems passing that requirement.

    Sarah Sands
    Senior Technical Specialist
    Golden Artist Colors



    Sarah Sands, Senior Technical Specialist, Golden Artist Colors
    2017-09-10 16:57:40
  • ApproveRejectUn-ApproveUser Comment

    ​Thank you for these in-depth and helpful answers, Sarah and Kristin. I will definitely rest easier now...

    2017-09-10 21:27:24
  • ApproveRejectUn-ApproveUser Comment

    ​Kristin, you mention "efflorescence" as a possibility between two different acrylics, and I'm wondering if that might have happened in another troubling instance of gessoing a support. (I queried this topic in the Forums under Cat Sprayed panels.) I wondered if the five panels I'd gessoed had been "cat sprayed" while daytime drying outside: the strong surface smell from the ArtBoards Gesso (a very absorbant gesso) over two coats of Golden's GAC100 size was, from the first gesso coat to the fourth and final, a very strong cat-urine sort of smell (not your usual drying acrylic ammonia sort of smell), which has hardly diminished at all in a month and a half of drying. I've never had this problem with that brand of gesso (a new jar), and the back of the panels which were also sized, then primed with Golden's own acrylic gesso (which I had on hand) does not smell that way. Or at least, it did NOT smell that way for a month and a half until I stacked all of the boards and put them in a corner out of frustration. The odorous front-side gesso surface has now transferred its odor to the backsides too. Whatever's going on, I fear these pricey and labored-over panels are, alas, garbage-bound...

    2017-09-11 13:04:04
  • EditDeleteModerator Answer

    Generally speaking efflorescence does not tend to generate a distinct odor....at least I have never heard of this occurring when it comes to materials used for easel paintings. So I do not think efflorescence is the culprit in this instance.

    Kristin deGhetaldi
    2017-09-11 22:01:15
  • ApproveRejectUn-ApproveUser Comment

    ​Thanks, Kristin.

    2017-09-11 22:25:35
  • EditDeleteModerator Answer

    Sorry to come in late on this one. Several years ago, we became aware that some factory-prepared canvases made in Asian countries had the residue of a release compound used to prevent sticking in the ​calendaring and rolling process. This compound was reported to have caused some issues with paint adhesion. The residue was removable by wiping with water. I don't know if it's still a problem at all, but ever since, when advising artists on using an unfamiliar, generic or private label stretched canvas, I have recommended wiping down the surface before use.

    Matthew Kinsey, Utrecht Art Supplies
    2017-09-14 22:30:21
  • EditDeleteModerator Answer

    ​Thanks for adding that note Matt.  We totally agree - and believe it was a similar issue that sparked our putting out an Advisory Notice to artists concerning Pre-Primed canvasses and how to both test to see if there is likely an issue (its a really easy water-drop test) as well as ways to help adhesion, such as the wiping down of the surface that you mention. That article, and a link to the testing process, can be found here:

    http://www.justpaint.org/advisory-notice-concerning-pre-primed-canvas-supports/

    http://www.goldenpaints.com/adhesioncanvas


    Sarah Sands, Senior Technical Specialist, Golden Artist Colors
    2017-09-18 09:57:01
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