The Drying Time of your Paint & How to Use Cobalt Siccative

Drying time is something that I’ve rarely had to worry about over the years, mainly because I had the time I needed.  But lately I’ve found it necessary to know more about drying times and, in particular, sometimes speed them up.

First, a quick lesson on some quick drying paints:

  • Raw Umber – I’ll often use this to “ink” a drawing to the canvas, or, if there isn’t a drawing, then I’ll use this to block in the composition.  Usually dries in 24 hrs.
  • Cobalt Blue- Also a fast dryer (in fact, I believe Velzaquez would sometimes mix this with another paint specifically for its drying properties); Charles Weed suggested I use this in tandem with the Raw Umber.  I have not yet done that, but will!

Not sure how long a certain paint takes to dry?  Well, you can always consult the Mayer handbook… or buy a tube of Michael Harding paint; he puts the drying time right on the label.

Speed Drying

Here is where the cobalt siccative comes into play.  The most important part is this: use it sparingly.  Only a “few drops” is what I’ve been told, but searching the web, I found a discussion about it on

Below are some quotes I thought useful.  I’ll soon run some tests using a cobalt siccative and walnut oil.  I’ll be sure to report back!

5 drops of cobalt drier should be used per each 2 1/2 fluid Oz of any given medium.

Cobalt Driers (of which cobalt naphthenate is the best grade) are safe enough if used with care. The general rule is to use as maximum, 50 drops of it per each pint of medium.

We have seen that the advantage of LEAD and MANGANESE siccatives compared to Cobalt is that Lead and Manganese dry the oil painting film from the inside out .
Of these, there have been some famous driers:

1. Siccatif of Harleem
2. Siccatif of Courtrai

Siccatives of Harleem have been discarded for a long time, because they were very dark and would tend to yellow and darken the picture.

Modern industrial practices have enhanced the methods of making Siccatif of Courtrai
There are 2 types of Courtrai Drier:

TYPE 1: Contains both Manganese and Lead salts and is the most powerful drier. Darker in colour, but modern industrial processes have managed to stop it from darkening pictures.

TYPE 2: Contains just Lead salts. Clear transparent it is not so powerful as type 1, but safer as it is safer to use with light colours or colours in which even a slight yellowing could pose problems.

The BEST Courtrai driers I ever experimented with and indeed used are manufactured by LeFranc & Bourgeois :

Product Ref. Code 1168 – Brown Courtrai Drier
Contains manganese and lead oxides

Product Ref. Code 3122 – White Courtrai Drier
Contains only lead oxides

MAXIMUM APPLICATION RATE: 1% to 5%, which means 2 to 3 drops of drier for a blob of oil paint of the size of a walnut.

These driers should be used only with slow drying colours, especially Brown Courtrai Drier. White Courtrai Drier may be used in the same proportions mixed in the painting medium.

5 replies
  1. Mit Koevoets-Augustin
    Mit Koevoets-Augustin says:

    Cobalt blue was not invented until 1802.
    No way Velazquez used it!!
    Maybe you are confused with smalt..

    Kind Regards

  2. Mit Koevoets-Augustin
    Mit Koevoets-Augustin says:

    Smalt is not the most practical pigment to use (low oil absorption, difficult to grind).
    It is said that when used as a drier, it would sometimes be sprinkled on top of drying oil layers.
    Its just my personal opinion but I believe its use as a drier is overemphasized because in those days the paint was hand-grinded which already offers a much shorter drying time than industrial paint.
    Its use would only have been useful in combination with certain specific pigments or as a blue pigment (because of the costs of ultramarine). Since Velazquez used mostly earth colors in combination with lead white, pigments with drying qualities in themselves, he would rarely have needed an additional drier.
    But, there are some that like to write about all the different kind of magical concoctions the “old masters“ would create in order to paint what they did who will strongly disagree with this.

    In my experience most people that have problems with drying times are using industrial mediums.

    If you do want to try smalt I would recommend that you buy the real pigment and not a tube.
    In general, making your own paints with good quality (cold-pressed) oils will also reduce the drying times of your paintings and increase your understanding of the pigments and its properties.
    Not to mention the piles of money you will save 😀
    In any case cobalt blue and smalt are totally different pigments; in practical use they dont have very much in common.
    If you need a recommendation for ordering pigments or help making your own paints give me a shout!
    I recommend

  3. alex
    alex says:

    please I have a problem with my white gloss: it turns yellowish after application. I use cobalt, zicornium and calcium driers. please could you help me fix it. thanks

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