• This topic has 10 replies, 5 voices, and was last updated 6 years, 10 months ago by Batman55.

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  • September 8, 2015 at 1:05 pm #993362

    I have been working on a large painting off and on for several months. I paint thin layers, but don't mix any mediums or oils with the paint. The last few weeks, I have tackled it, but I've noticed the new paint I have applied is scratching off with my fingernail. Only the white paint or paint mixed with white. I used walnut oil to oil out once in awhile, but the last time I did that was a few months ago. My paint is good quality: M.Graham and WN. I was thinking I could sand down the areas where the paint is scratching off, but for all I know it could be a prob with the whole painting. Any ideas?

    September 9, 2015 at 10:59 am #1237848

    Hi bfoxart,

    I have had that happen to me before on gessoed board, and best I could tell it was a problem with me not preparing the surface properly. For you, I'd guess it's either the preparation of the previously painted surface, or the new paint layer is too thin maybe? Perhaps oiling out between each layer would help.

    Meg

    September 9, 2015 at 11:32 am #1237845

    Is the pant that is scratching off dry and powdery or more flake-like? It is either too thin and underbound, or the paint layer didn't adhere properly for some reason.

    Lady Mars Orange Marmalade Stapleford
    Moderator: OIls, Pastels, Plein Air
    Be yourself. Everyone else is already taken. -Oscar Wilde

    September 9, 2015 at 11:37 am #1237846

    Look at Ron's response in the No medium/time between layers.. thread.

    Lady Mars Orange Marmalade Stapleford
    Moderator: OIls, Pastels, Plein Air
    Be yourself. Everyone else is already taken. -Oscar Wilde

    September 9, 2015 at 3:15 pm #1237853

    Hmmm.
    this is what Ron said:
    Oiling out, or painting into a couch, is not necessary at all.
    Just wait until your paint feels dry and paint over it.
    Oil will cross link chemically with the paint underneath so you don't have to be concerned with adhesion. On the contrary, if you add more and more oil, your paint will become more and more glossy to a point where it will definitely effect adhesion.
    __________________
    Ron
    http://www.RonaldFrancis.com

    I think the last sentence may be my problem. The previously painted area had been oiled, but I didn't paint on it when the oil was wet. Now it is very glossy. Still, it's odd that only the white or mixed-with-white paint is not sticking. I am going to try sanding a small area and see if that helps. I hate to give up.

    September 9, 2015 at 7:04 pm #1237849

    Difficult to know what's going on there.

    Is the paint peeling off with your fingernail, like thin rubber?
    How long has the paint been curing?

    It may be that adhesion could improve over time as more cross linking occurs.
    I don't know how long cross linking takes place, or how it slows down over time. Maybe Sid knows more about that.

    Walnut creates a weak film, so I wouldn't be using it to oil out unless you're painting into it wet, and even then, just the thinnest layer possible.
    It's certainly not a good idea to oil out to the point where the surface is glossy as it is only meant to feed matte areas enough bring out the saturation of the colours. Very useful when continuing to overpaint an area.

    If you don't want to wait to see if adhesion improves, and if this is on canvas, I would possibly rub with solvent rather than sand.

    Ron
    www.RonaldFrancis.com

    September 9, 2015 at 9:20 pm #1237850

    My two cents worth….not an expert like Ron but I still find this odd that it is only occurring with the white paint or mixed-with-white paint. Walnut oil is more slippery in my experience than linseed and I wonder if the white paint has a walnut oil binder and simply needs to cure longer but does sounds like there's too much oil there so it's too glossy and smooth for the paint to adhere. Definitely solvent would help to roughen-up the surface.

    September 10, 2015 at 12:30 pm #1237854

    Thank you, this is valuable advice! My white paint is M.Graham, which is processed with walnut oil. I got a little carried away with oiling out, not knowing that it should be painted on while wet. My solvent is OMS, would that work? Would it take off the old oil or just rough up the surface?
    The new paint is very thin, and is scratching off like it is not dry yet, not exactly peeling. It does feel dry to touch though; not sticky. Someone suggested our very humid weather might be playing a part.
    I appreciate your responses very much.

    September 10, 2015 at 12:35 pm #1237847

    Yes, if it isn't really dry then OMS should take it off. Good luck, this is a frustrating problem for sure!

    Lady Mars Orange Marmalade Stapleford
    Moderator: OIls, Pastels, Plein Air
    Be yourself. Everyone else is already taken. -Oscar Wilde

    September 10, 2015 at 12:59 pm #1237851

    You could try OMS and if not working, try regular Mineral Spirits since it's a stronger solvent. Kind of a mystery but sounds like too much oil and needs to dry longer considering your humid climate. Solvent would definitely roughen up the surface enough to help the next layer bond. In the future, it is helpful to know that oiling-out should be wiped off well so only a very thin layer is left.

    September 10, 2015 at 1:07 pm #1237852

    And I meant to say that I only oil-out when the painting is done and touch-dry because as Ron says in the link above, it isn't necessary during the painting process. I only oil-out at the end to get rid of surface differences – matte and gloss areas – because even varnish in my case doesn't seem to take care of it.

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