I looked at previous posts but still find the advice I’ve seen on using alkyd mediums a bit confusing and contradictory. On one hand I’ve read that it is best to use alkyd mediums only in lower layers because you want faster drying layers under slower drying layers. This makes sense to me. However, I’ve also seen recommendations from manufacturers to increase the amounts of alkyd medium in subsequent layers to maintain fat over lean (more flexible over less flexible?) but that seems to contradict the slow over fast drying concept. Ultimately, I would like to use M. Graham solvent free walnut akyd medium in the underpainting/blocking in and then straight oils in subsequent layers. Would I need to worry about a) adhesion between the first and second layers or b) violating fat over lean/ more flexible over less flexible?
”pre-made alkyd paints .. contain a minimum of binder,” The existence of alkyd “underpainting” paints led to my incorrect assumption that one could substitute alkyd medium + paint in the first layer – so that is definitely cleared up. I’m still a little confounded that the manufacturers recommend starting with a small amount of alkyd medium and adding more in each subsequent layer – to increase flexibility (fat content) as one would with stand oil. But, I understand that extra alkyd medium would also increase drying rate which is undesirable in successive layers. Hmmm.
Brian, what would you recommend using to speed up the drying of initial layers of paint? I don’t want to use alkyd based paints and it doesn’t look like using them there would be a good idea.
You are correct about the conundrum. It is generally best to have lower layers dry faster than upper layers and to have upper layer more flexible and generally fatter than those below them.
I would suggest that when adding medium to a paint, as opposed to underpainting with pre-made alkyd paints which contain a minimum of binder, you only use it in the final paint layers. In ala prima paintings this may be the first layer and in more complex paint layering it may be the 7th or later layer. This also means that you should really let the lower layers dry well before applying the final layers. You should also refrain from using poor drying and weak film forming paints in the lower layers unless they are a part of a mixture containing better film forming paints (ie ivory black should have a good amount of white added to it when used in lower paint layers)
Does this clear things up at all?
Again, you are not completely wrong about the contradiction. Adding larger and larger amounts of fast drying alkyd mediums to subsequent oil paint layers does mean that the top layers would dry faster than the lower layers. In practice, this is a matter of degree. Small incremental differences will probably not cause a major problem in terms of drying differences and the added flexibility of the later layers would conform to the preferred practice of more flexible on top of less flexible.
Alkyd mediums have been in use for a relatively good length of time and the practice of judicious additions these to traditional oil paint does not seem to have caused problems.
If you are diametrically opposed to the use of alkyd mediums despite their good track record, there are a couple of options. Choose only paints composed of fast drying pigments (lead white, umbers etc) or the judicious addition of driers. I am adapting one of my responses to another thread as it is applicable here.
I generally do not recommend that artists add driers to their paints and mediums because it is way too easy to add more than necessary and risk compromising your paint film over time. If you performed systematic tests and only added just the amount necessary to make a paint that dries in a reasonable amount of time (a couple of days) this should be safe. If it were me, I would make up a batch (eg 8 oz) of your chosen solvent (eg odorless mineral spirits) and add a few drops of drier. Then add this to a blob of paint diluted in the manner that is typical for you. Test how many days this takes to dry. If it is still too long, add another couple of drops and try again until you figure out the proportions necessary to create a drying rate that meets your requirements. Do not add more than necessary.
Others may have additional thoughts.
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