Cobalt Drier

I normally want my oils to dry slowly so I love the Geneva paints, and also Mark's recipe for slow dry medium.  However, I'm now venturing into plein air painting and want my plein air paintings to dry faster.  So have been looking into different fast dry mediums for use with regular oil paints.

I would NOT try to use a fast dry additive with Geneva!

Has anyone Used Cobalt Drier?  I have a bottle of the Grumbacher Cobalt Drier, and the only information I can find on how to use says to add is "sparingly by drops" to the medium, and not to the paint.  I can find nothing on how much medium per drop.   It seems that there would be a recommendation as well as a warning on how much is too much.

Is anyone aware of any recommendations on using cobalt drier other than "sparingly"?


  • edited July 2021
    I use cobalt in my medium which is made from one ounce of linseed oil and one ounce of OMS.  To this, I add about 5 drops, more or less, of Grumbacher cobalt.  I say more or less because I don't have a dropper.  I use a palette knife dipped into the cobalt, and then let drops slide off the knife into my medium.  Sometime I get more, sometimes, less,  but it works like a charm.  Paint is mostly touch dry by the next day.   You will have to play with it for awhile to find the amount that works for you.  Just don't use too much.  Count it out by drops, and in your medium, not your paint nuts.
  • Thanks @broker12 !  Exactly what I was looking for.  

    Even Ralph Meyers is rather vague in "The Artist's Handbook"!  

    If I make any changes, it will probably be to use less cobalt.

  • I've been wondering about something like this. I didn't know there was such a thing. If I understand correctly, you add cobalt to the medium and it makes the paint dry quickly. I want something that will dry paint overnight so that next morning I can paint over it without the colours mingling.  I generally paint wet in wet but there are times when this doesn't work for me and from what you guys have been saying this would do the trick. Even if it's only semi-dry with a skin on top would be ok.  I could still put more fluid paint on top of it without the colours mingling. I'm going to see if I can get some of this. 
  • @tassieguy if you search for "fast dry mediums", you'll find a lot available.  Liquin seems to be the most commonly used.  HOWEVER, in reading up on the characteristics of different fast dry mediums, I found that they can harm the paint film, so I started looking for a better alternative.

    According to Ralph Meyer in his "The Artist's Handbook" proper use of a cobalt drier is the "least harmful" of the different driers.  But he doesn't give much information on how to use it.

    The recipe given by @broker12 gives a starting point by someone who actually uses it and has had good experience with the recipe!  
  • I used to use Liquin in the same way as I now use Grumbacher Cobalt.  But deep down I never did like it.  I don't know why, exactly.  After several years of using a bit of Liquin mixed into my medium, I decided to try cobalt.  Again, not sure why I like it better, but I do. 
    There is no particular reason I use Grumbacher Cobalt.  I started with and it did what I wanted so to stuck with it.
    tassieguy . . . it won't take you long to figure out how much cobalt to mix into your medium to make your paint touch dry by the next morning.  I've been doing it for years.
  • Thanks, @mstrick96 and @broker12. I'll pick up a bottle of it when I go in tomorrow to get some new brushes. :)
  • @mstrick96, @broker12 and @tassieguy,
    I have just read in on a sales page of amazon for this product “An extremely strong additive for oil paints and should be used sparingly. Overuse may cause cracking of paint film when drying”.

    I have been using M Graham`s Walnut Alkyd Medium for a few years and it dries the paint speedily enough for me.
  • edited July 2021
    Cheers, @MichaelD. I think you're only supposed to use a tiny amount - a couple of drops in a jar of medium. My paint takes a few days to dry because I don't use a medium with solvents - just walnut oil - so this product would be quite useful. But I'll be careful with it. Thanks for the heads up.  :)
  • Pigments with Manganese (like burnt umber) dry quickly as do Iron oxides (Venetian red, Indian red). Most organic pigments (Hansa yellows, pyrrole reds) dry slower. The main exception is phthalo blues and greens which dry quickly.

    You can find more driers in student grade paint as some dry very quickly while other brands take much longer for the same pigment.
  • edited July 2021
    I guess the bottom line is that I'd like some control over what dries when. So, I would not add dryer to the earth colours like burnt umber and manganese violet ( a favorite of mine) but would add it to organic pigments (except the phthalos) so they dry about as quickly as the earth colours. Is that right? Damn, painting is a complicated business!  :)
  • @tassieguy, I would be minimizing my use of driers anyway.  I prefer my oils to dry slowly, so my favorite is Mark's Slow Dry Medium recipe. 

    I'm experimenting with other mediums and an considering a fast dry medium for plein air work.  If I make my own, I can adjust the formula  to meet my needs.  
  • I bought a wee bottle of cobalt dryer yesterday and am starting a new painting tomorrow. I'm going to try the drier for my dark underpainting so I can get on with more detailed, lighter coloured work the next day without the risk of it and the underpainting running into each other. 
  • Let us know  . . .   be interesting to know how it's going for you and what your think after a bit of use.
    You know, for grins and giggles, you could put together, say, a couple jars (small) each with different amounts of cobalt, and then paint some strips or blobs on some studio scrap and see how it goes.  Use some fast drying paint and some slow drying to get an idea of what to expect.
  • Good idea, @broker12. What I'm after is the knowledge to be able to control what dries when and your idea would be a good experiment in that regard.  :)
  • @tassieguy I’ll be interested in the results of your experiment.  Wear water impermeable gloves when handling cobalt drier.  If it is in fact cobalt based.  They do make a non cobalt based drier now as well.  I’m big on using nontoxic materials so I take great precautions and read materiel safety data sheets.  

  • I'll let you know how it goes, @GTO. Thanks for the heads up about toxicity. The woman in the art store here also warned me about it so, yeah, extreme caution. Smells awful.  I should be more careful generally when painting. I don't know how many times I've packed up for the night and gone to wash my hands and found them (or other parts of myself) smeared with cadmium yellow or red. 
  • @tassieguy I wear nitrile gloves when I paint for that very reason.  It’s easier to clean up afterwards.  
  • @tassieguy. Yeah, it takes about 10 minutes fir me to clean my brushes (using walnut oil).  Using the gloves saves me a lot of time from cleaning paint off my hands.
  • edited August 2021
    Well, the cobalt drier works. In fact, after about 45 minutes the ultramarine violet I'm using as a base tone for rocks starts to tack up and I can paint over it with a soft brush and fluid paint without it dragging into the lighter colours that I put on top.

     I used very little. Almost nothing. I just dipped the tip of a palette knife into it and then stirred it into a small jar of the walnut oil I use as a medium.  If I leave it overnight the violet underlayer is absolutely touch dry. When mixed with lighter colours they also dry faster. I hardly blend at all and I like things to dry quickly so I can do further work on a painting. So, if you are working on something that you want to dry quickly the cobalt drier works great.

    Seems every painting I do I learn something new.  Thanks to @mstrick96 for telling us about cobalt drier and to @broker12 for relating his experience with it.  :)
  • Glad it is working well for you. 

    Just be sure to treat it with respect, because it is potentially toxic.  Of course a lot of the other chemicals we use are potentially toxic and we have to treat them with respect too.

    Bob Ross died from lymphoma, probably because of the way he cleaned his 2 inch brush in odorless mineral spirits by slapping it on his easel.  I cringe every time I see him do that!  Vapors everywhere!  What he used is the stuff from the hardware store too!

    Jerry Yarnell almost died from lymphoma for the same reason.  His doctors told him that was that cause and to stay away from mineral spirits because his system is now very sensitive.  He switched to acrylics. He was constantly in the mineral spirits, and absorbed it through his skin and breathed in the fumes.  

    On the other hand, if good chemical handling practices are used and these chemical are treated with respect as they would be  in a chemistry lab and with proper ventilation, the modern oil painting chemicals can be quite safe.  

    In other words, don't get it all over yourself and don't breathe in the fumes constantly!  Used properly, the cobalt drier is used in such small amounts that it is safe.  
  • Cheers, @mstrick96. It's so easy to forget that the materials we use are toxic. I'm going to start wearing gloves because I'm always getting heavy metals like cadmium on myself without realizing it. I try not to use solvents. I've mostly just been using walnut oil as a medium but it takes a long time to dry which is why I was so interested in the cobalt drier.  :)
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