Weird spots on background

I mixed white , burnt umber and ultramarine to make this grey  , all Geneva . And now I get these dark splotchy things . Are they oil spots ? What would I do to fix this , if possible . 
And what causes it. 
I have had this once before 


  • edited October 3
    It look like a bit of  incompletely mixed ultramarine. Just paint over it with the grey. 
  • Annie

    Agree with Rob. Also may be just an errant dab with a darker tone. Or less likely a patch of sooty mood coming through from a damp canvas.

  • @dencal And @tassieguy

    its not ultramarine. They’re oily and painting over them isn’t covereing . 
  • Well, in that case it's something on or in the canvas that must have been there before you painted over it. Not knowing what it was, I'm at a loss as to how to deal with it. Have you tried just painting over it with the grey?  
  • edited October 3
    To me it looks like some kind of contamination on the surface before you applied the paint. Either that or grease from fingers or something like that after the paint had dried?

    Is there anything different in how you prepared this surface before starting the painting?
  • @tassieguy @Richard_P

    i didn’t prepare the canvas. 
    I searched around a little and most replies are that it’s the medium used .
    I didn’t use anything but Geneva. 
    Haven’t touch the surface with my fingers .

    This happened a few times before and I tried psinting over it or oiling out .. but Weird 
  • That's happened to me too, Annie, several times and I have no idea why.  :(  I can relate but sadly I can't help :(  Hopefully it gets figured out.
  • @allforChrist

    sorry that it happened to you . Though it’s good to know it’s not just me😁
    Could it be the clove oil I wonder . My burnt umber is super runny.
  • CBGCBG -
    edited October 6
    Mark talks about oil paint separation here (go to the 6 min mark), not sure if that helps:

  • Annie

    I don’t think it is worth worrying about, hardly noticeable.

    However, should you wish to remove (over painting unsuccessful) the spots then I suggest a careful excavation with sand paper, scalpel or blade. The watch point is whether the spots reside in the paint or do they come through the support and paint.

    Is there anything on the back of the canvas at that point?

    Having scraped back seal with a blocking primer and several coats of grey. The ‘mending’ needs to be invisible before varnishing.

  • CBG said:
    Mark talks about oil paint separation here (go to the 6 min mark), not sure if that helps:

    Ah, that’s helpful . Thank you very much mich !
  • @dencal

    This is canvas paper . It happened to me before with the same grey from burnt umber , ultramarine blue and white .
    At that time it was very noticeable .

    I will try painting over it once it’s dry : I use a soft blender to try to wipe it out when still mid-wet and it helped a little . The grey is much lighter than the spots .

    Thank you ,I appreciate it. This forum is so wonderful !
  • Annie - I  have had the exact same experience a few times. It was always on Canson canva-paper, used with no additional ground. Now, I apply a ground and have not had the problem again. I suspect it is caused by a manufacturing flaw on an area on the canva-paper - maybe not getting the same amount of sizing. 

    I use Canson canva-paper for studies. for more permanent paintings, I use Arches 100% rag oil paper. I always apply an additional ground.  
  • @Desertsky
    That is good to know !
    From what I could find , the common denominator seemed to be around medium used. So I figured it was the oil. 
    The weird thing is : I paint on canson and it doesn’t happen the other times . And it is not on one spot , it is all over . Maybe a misfit in the pad !
     I read somewhere else that gesso could warp the paper but I’m not sure why that would be . 
    Would gesso on canson then not be enough ? 

    I will try some Arches , thank you so much for the recommendation. I appreciate it !

  • Annie - regarding "gesso" and paper: When you write "gesso" I think you mean acrylic or oil ground or priming. I would never use real gesso (glue and calcium) on any flexible surface because gesso is not flexible and will crack. 

    Applying an acrylic ground on paper will cause it to warp a little because the water in the ground will swell the paper as the ground is absorbed and before the water evaporates. The larger the sheet of paper, the worse the warp.

    I control - and almost entirely eliminate - the warp by taping the 4 edges of the paper first, applying the ground, letting the sheet dry, and then by applying the ground on the back of the paper as well. In my experience, paper moves much LESS from humidity changes than cotton canvas, even after the canvas is sized and primed. 

    BTW, I think that both Canson canva-paper and Arches oil paper are long-lasting surfaces to paint on. When people write that paper is not a durable surface, I suspect that they are not making the distinction between regular wood-chip cellulose paper and buffered 100% cotton paper. If I like a painting I have done on paper, I glue it to ACM or sealed hardboard and it will last centuries. Fighting words I know. :) 

  • @Desertsky

    That is so good to know . Thank you very much !

    I will try this , very helpful .
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