Why is this happening?

I painted this on oil primed linen glued to an mdf board using Miracle Muck. As it was drying little dark blue spots formed. I painted over them and they went away. Then they came back again. Does anyone know why this is happening?
[Deleted User]cynthiagwilsonSummerjcdrGerard


  • MDF contains lots of glues and resins, including formaldehyde, so it could be leaching through the linen..... unusual for it to get through oil primer though, unless it was a very thin coating.

    I make my own linen panels on MDF, although formaldehyde free MDF is available, it's very expensive, so I use ordinary stuff. However, I use archival pva glue, then double coat it with 'sizing', then apply several coats of gesso, then prime with lead, W&N flake white. Never had any problems.... but then I probably go overboard on the prep!
  • Beautiful painting Ronna! I've used mdf quite a bit ...both with linen glued down (using both Miracle Muck and archival glue) and painting directly on the mdf with no surface preparation at all. I've never seen the problem your describing. As you well know several of us on the forum have/do use mdf and I've not seen anything like what you've described mentioned. Could be something funny with your piece of mdf but I wouldn't rule out an odd piece of linen...I might suspect the paint if the spots showed up in different places on the surface after you repainted it. If you have any of the mdf that you cut for this painting, you might take a small mdf piece, put a small piece of linen, etc = repeat the process on a smaller piece. Hope you can save your wonderful painting!
  • Don't think we helped you at all in finding an answer...may have to chalk it up to one those little life mysteries. Let us know if you are able to save it.

    Your second painting is so wonderful...love the subtle colors, the boats (beautiful details) anchored on the white buoys (great shadows on the buoys) and the reflections of the boats on the water (nicely broken up with the tiny swells). Your air to water transition is just perfect for those dull light, cool mornings along the Maine coast! The shape of your canvas really plays to the composition. Can you tell how much I like this painting?! Congratulations! =D> :)
  • Yes, Ronna, it is a beautiful painting. just llove how you did it, so soft and lovely, the colors, the water. the sky, the boats. Just Beautiful.
  • I remember that happening on the 3rd or 4th painting I ever painted, it was a prestretched cotton acrylic (gesso). I never solved it, it's still visible today. Interestingly, it was a marina scene like this.
  • Those paintings are REALLY good!!!! Just fantastic!!!
  • That's interesting Mark. I guess it will remain a mystery. I painted these from photos I took in Maine. I can at least frame and hang the second one.
    Thanks everyone for your kind comments.
  • What they said.

    mnsrc said:

    I do not, but may I say that I love love love your painting.

    What he said!
  • Holy crap, Ronna, what a stunning painting!!! I need to get on the forum more often. In terms of the blue spots I'm going with the leaching of something or maybe a mold?
  • Good thought about the mold Garry....might be interesting to what info there is about that or if any members have experienced that particular problem. Maybe all the water in Ronna's painting caused the problem?! The water was just to real! ;)
  • Amrit and Garry, thank you.
    Mold? Can mold form in one week? It was in the drying process when the spots formed. Now that I'm thinking about it I had to get really close to the canvas because the boats were so small. Maybe I was breathing on it?
    Karen, thanks for the link. From what I got out of the information Muck is a good adhesive and will not cause problems over time but is not easily removed so is not recommended as a conservation adhesive. So the question is, will we ever need to remove the canvas from the board. If yes, then don't use Muck. Something to think about.
  • My guess would be mold, it feeds on paint, glue, just about anything. there are mold killing primers now that painting contractors use on interior mold problems, you might be able to reprime those areas and repaint. And yes, mold be come up in overnight, so a week is all the time it needs to appear.
  • Thank you Whistler. I'm thinking now that it is. I have plans to start over and repaint this again one day soon.
  • Ronna

    I don't think it is mold. Clove oil is a great killer of mold. Are you using standard SDM?
    i don't think it matters it is a very slight color shift, probably pigment contamination.
    What about darkening the gray fog a notch to match the spots?

  • Ronna! These are sooooo good! Thank you for the "eye candy"
  • Denis, yes, I used the SDM. I think I'll just do a new painting.
    Sue, thank you!
  • Ronna, I know it's been a year since the last post on this thread but take heart. I SIZE all my substrates several times before the gesso layers. That keeps the action going on in the substrate from intermingling with the gesso and the paints. And vice versa. They are constantly going at it. It never ceases. I'm reminded of this every day because we've got the same thing going on in our bathroom. The walls are oozing orange spots through the outer layer of white--just like in your paintings. Heartbreaking when I look at your magnificent work. They are so wonderfully eerie.
  • Beautiful paintings Ronna.
  • Thank you Summer for your input. Interesting how that's happening on your walls.
    Thank you Irishcajun.
  • Absolutely stunning painting. What a heart breaker to have those spots come up. Sincerely hope that won't happen to you again. Your work is so beautiful, I don't want to think of things like this happening to your paintings.
  • Oh, thank you oilpainter :)
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