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  • Anodized Aluminium as a painting support.ApproveRejectUn-ApproveSubscribeUn-Unsubscribe
    Question asked 2017-04-09 11:54:22 ... Most recent comment 2017-04-11 18:23:00
    Rigid Supports
    Question

    ​I recently found online a kind of artist ACM panel with an anodized surface. The store that makes the panels claims the surface is porous enough to paint on directly with oils and acrylics, although I'd personally want to prime the panels first. Anodized aluminium as a painting support seems quite uncommon - however I did find at least one well-known artist, David Dunlop, who regularly uses it. And so I was wondering, are there any problems associated with priming then painting on anodized aluminium? As always, any advice would would be appreciated. Many thanks, J.

Answers and Comments
  • EditDeleteModerator Answer

    The main concern with painting on ACM panels is always adhesion. You want to ensure the surface is prepped in such a way that you do not encounter scaling, flaking, delamination, etc. down the road. In the meantime we have sent your query out to some who are more knowledgable in this area who may be able to weigh in with their expertise.

    So anodized aluminum surfaces can really range in the sense of composition (e.g. is the aluminum sheet itself an alloy as opposed to pure aluminum? You might want to avoid any zinc-containg alloys for example), pore size, and the method used to seal the pores after the anodizing process has been completed. So it is really hard to say whether one particular brand/type is better than another without doing a number of tests.

    In principle we feel it that painting on these surfaces would not pose too many risks if the surface is properly prepared. For surfaces that possess polyester coatings (an alternative to anodizing that industry uses to counteract potential corrosion) we recommend degreasing, lightly scuffing the surface to provide tooth, and then applying subsequent layers of primer and paint. We are unsure at this point if lightly sanding the surface of anodized aluminum would be necessary or even a good idea (just as with polyester coatings you do not want to abrade TOO heavily as you risk removing this protective layer entirely). This may very well depend on the thickness of the anodizing layer. But you could certainly ask your manufacturer whether using a 320 grit sandpaper (which is what we recommend for polyester coated ACM…you may need to use a finer or coarser grit depending) would ever get you close to the bare aluminum underneath for a particular brand of anodized aluminum. As for painting directly onto the surface without sanding, again this would require additional tests for any given brand. If the manufacturer states that it is alright and you chose to forego performing any tests yourself then things might work out fine….if not then the manufacturer should not be surprised when they receive an unfortunate phone call from you.

    Even though we tend to advise folks to steer clear of most industrial products, sometimes there are certain instances when one actually SHOULD turn to industrial products to ensure the longevity of their work and with ACM this can certainly be the case. DTM Bonding Primer by Sherwin Williams has been tested and found to be a suitable primer for ACM, a primer that can then be covered with a layer of acrylic gesso (followed by acrylic or oil paints).

    For piece of mind you can always adhere a canvas to the support first before applying any size/primer, ground, paint, etc. That way should there be any issues in the future the canvas support can be safely removed from the problematic ACM panel and simply re-adhered to another rigid support. There are instructions and additional information relating to this process as well other aspects of ACM that can be found in our "Rigid Supports" document in the Resources section. 

    Kristin deGhetaldi
    2017-04-09 17:18:41
  • ApproveRejectUn-ApproveUser Comment

    ​Thanks Kristin. I was hoping the anodized aluminum would offer better adhesion than Dibond, and wouldn't need a bonding primer. I'll try emailing the art store for more information about the panels. However, the treatment of the panels' surface is described as "proprietary", so chances are I'll receive assurances, but not specifics. I can always order a sample piece and do an adhesion test. But if the acrylic gesso looks to be adhering well - after a week, or even after a couple of years - does that really indicate good adhesion after, say, a couple of decades? I hope that doesn't seem a silly question. I'm just thinking of a number of painters, David Kassan springs to mind, who use Dibond, and prepare it by scuffing, cleaning and priming it directly, and skip the bonding primer step. I don't think anyone has had problems with adhesion, yet. I think George O'Hanlon also feels that priming Dibond directly should be safe. The impression I get is that if a primer adheres well to Dibond in the first place, the pvdf surface of the Dibond is ( is inert the right word? "chemically uneventful" ) enough that the primer should remain well-adhered over the long term. Hopefully the same would apply to anodized aluminum. Or have I misunderstood, and is a specialized primer like Sherwin-Williams DTM always recommended as a bond coat on Dibond, regardless of how well a particular acrylic primer might perform in an adhesion test? J.

    2017-04-10 02:13:50
  • EditDeleteModerator Answer

    ​These are all very good questions...in the sense that they are unanswerable from the point of view of a conservator simply because not enough time has transpired for us to say one way or the other. This is why we tend to lean towards the more "conservative" suggestion of adhering a canvas down first JUST in case there are issues later on down the road. But there very well may not be any problems...in either case do consider recording whatever you choose to do on the back of your panels.
    The point of the primer coat is to promote better adhesion...but if tests demonstrate that certain methods are working fine without a primer (I recall that earlier tests using true gesso, meaning animal skin glue, did not pan out and lead to cracking and delamination) then the primer coat may not be necessary for certain layering systems and/or certain types of aluminum substrates. Hopefully some of our other moderators will weigh in on this...I will also try to reach out to some objects conservators who may be able to shed some light as well.

    Kristin deGhetaldi
    2017-04-10 11:52:48
  • ApproveRejectUn-ApproveUser Comment

    ​Kristin has described an instance where a primer applied to the surface of ACM has demonstrated good adhesion. GOlden did tests with two different commercial DTM primers, Golden acrylic gesso and acrylic paint with various results—the DTM primers exhibiting the best adhesion in these tests. Natural Pigments is conducting adhesions tests of various commercial primers and paints on ACM to determine what can be adhered to specific panels as a guide to artists like the poster. Mounting substrates, such as canvas, is of course the best option at present until we have more definitive information from adhesion tests, such as those made by Golden Artist Colors, Natural Pigments and other companies. In regards traditional gesso and chalk grounds we found varying adhesion and we are working on a protocol to be apply these grounds to ACM panels, but at present have not concluded our research and recommendation.

    2017-04-10 23:55:32
  • ApproveRejectUn-ApproveUser Comment

    Thanks Kristin, and to the second moderator too ( apologies, I can't see a name ). So, in lieu of specifics, might we say anodized aluminum is an "experimental" support? 

    In any case, regarding Dibond, it's good to be aware of the safest option, mounting fabric to it. 

    I know many of us will be eager to see the results of the tests done at Natural Pigments, and appreciate the time and resources that go into that kind of testing. I'll definitely be checking the Natural Pigments forum regularly ( assuming the results will be written up there ? )

    Thanks for taking the time to consider my questions, it's always appreciated. -J.


    2017-04-11 13:20:12
  • EditDeleteModerator Answer

    ​The last User comment (with time stamp 2017-04-10 23:55:32) would be George O'Hanlon from Natural Pigments...
    But I would say "Yes," anodized aluminum is likely fine but we really cant say for sure without doing more testing. 

    Kristin deGhetaldi
    2017-04-11 13:43:17
  • ApproveRejectUn-ApproveUser Comment

    ​Thank you Kristin - and thank you George O'Hanlon. :)

    -J.

    2017-04-11 18:23:14
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