Alligatoring - how to address it

edited September 6 in Drawing
Oil on board. Gamblin oil ground. I realised too late that the second layer of ground was probably too thick and oil settled on the surface. This gave me adhesion problems due to lack of tooth. I lightly sanded the areas I hadn't painted and it solved it. But in other areas this textured pattern had already happened.
This is just very initial underpainting - a sketch really because my subject has so many architectural details I needed good placement with. I used liquin to thin the paint and help it dry more quickly - bad move really, I now realise. It resulted in this texture. It's not cracked, it's just raised in tiny ripples. I didn't think anything of it when I first saw it as I assumed i could just paint over it. George O'Hanlon on another site called it alligatoring and said the only solution was to remove the offending layer of paint. I've asked for clarification and haven't heard back yet.
There are many, many hours invested in this large work already, including blocked in faces of my four children. This appears in maybe 10% or so of the work - on the sides which I intend to darken as the work has chiaroscuro.
My questions:
1. Is this considered a big flaw in art if this kind of texture is seen anywhere on the canvas? Like - art shows and artists would write off this work? Obviously it wouldn't look as obvious as this.
2. Have you experienced this before and found solutions? Other than remove the paint?
3. Is it possible to paint over it without the texture coming through?
4. Is it ok to lightly sand it (eg1200 grit) with sanding block to remove tops of tiny ridges? Of course, they will show up as different colour and might need opaque paint to rebuild again.
5. If I have to remove it, what is the best way? Some other areas had multiple layers of glazes - with liquin.
I'm discouraged I have to say.

Comments

  • dencaldencal -
    edited September 6
    Abstraction


    https://www.corrosionpedia.com/definition/1906/alligatoring

    Alligatoring

    Last updated: April 9, 2017

    What Does Alligatoring Mean?

    Alligatoring is the large formation or pattern of shallow and deep cracks, whichlook like the skin of an alligator or crocodile on the surfaces of:

    • Paint with limited flexibility, excessive thickness, top coat that did not bond well or shrunk faster than the underneath layer
    • Hard paint over a softer or partially dried undercoat/primer
    • Bitumen, asphalt
    • Other coating materials that have been overexposed to the environment or are too old

    Alligatoring is also called crocodiling or chip cracking.




    From my reading and observations I don’t think you need to SNAP to it to fix. Caused by shrinkage and a failure across the van der Waals bonds in a material.

    This crazed pattern in fresh paint is very shallow and pretty stable. (Ain’t seen a pic yet) On old paintings and ceramics this is a desirable feature that people pay thousands for.

    One suggestion is to gently heat the surface. Experiment with hair dryer, heat gun or leaving in direct sun.

    Else, scrape back affected area/s and apply a tinted primer to refresh the surface tooth.

    Denis

    Abstraction
  • edited September 6
    I can't see a picture of what you're talking about @Abstraction but recently I noticed a sort of rippling texture on a painting I was doing. You may remember the discussion in another thread about my error with lighting and using a tablet screen. Well, I had to repaint that picture and hoped I'd just be able to just paint over the top of what I'd already done. I tried that but I got that rippling effect you speak of. The paint beneath wasn't fully dry and I had lost the canvas tooth and so I think adhesion was a problem.   Anyway, instead of painting over I realized I'd have to scrape down before repainting. That seems to have solved the problem but I should have scraped down more carefully as there are still a few problem areas.  So, I think O'Hanlon may be right.  Scrape down and repaint.


    Abstraction
  • 'Scrape back'. How do you scrape dry paint off? Without gouging?
    Is there any problem with using wet and dry sandpaper? When using a firm sanding block it can target the ridges and level it without having to remove everything.

  • Ah, yes, I forgot it was dry. Sanding back sounds like the way to go. 
  • I contacted Gamblin. I indicated that it was at least a month before I started painting.

    Response from Gamblin: "Oil Ground cures very quickly. After 1 month, your ground would be fully dry- even if the 2nd application was applied in a thicker application. The 2nd layer may have been too slick and needed tooth.

    The first coat of Oil Ground should usually be touch dry in 2-4 days. A second coat takes another 3-5 days to dry and cure in warm weather and 5-7 days in cool and/or humid weather. Temperatures below 65F and/or high humidity may add several day’s dry time. In general, plan for 7-10 days from start to finish before painting on freshly applied coats of Oil Ground. Again, the thinner the layers, the faster it will dry.

    If the Oil Ground was applied thickly and dries to a slick finish, lightly sand with 150 grit sandpaper to reestablish surface tooth.

    Yes, it’s more likely that an “over smooth” surface of ground + using a fatty oil medium caused these rippling / wrinkling issues.

    Sanding back the surface will help and you can start over. Our other advise would be to dilute your alkyd medium with some Gamsol or another mineral spirit to lower fat content, which would be more appropriate for an underpainting technique. What can also cause rippling or winkling is when too much fatty medium is added to oil color. Diluting the medium by cutting it with some solvent will likely help prevent this."

    She confirmed that I don't need to remove all the paint (as someone on another site suggested there might be 'traction' which could cause potential cracking later), but I can sand back the just ridges as long as I have sufficient tooth for the paint to adhere.

  • Thank you for passing this information on.   I am sure it will benefit many of us at one time or other.  Looking forward to seeing the end result.
Sign In or Register to comment.