Dear Marten: Cobra Dry Time
I have an acrylic background and am used to paints drying very quickly. I am currently using the 6 x 20 ml introductory COBRA set, and am somewhat puzzled at the extremely slow drying time (2 days now and still smudgey). How many days would you say it takes to "dry" ?
Thank you for your help,
Cobra is a true oil paint, with the addition of a vegetable based emulsifier which allows the use of water as a solvent. As with other oils, the primary binder is linseed oil, and it will have a much slower drying time vs acrylics.
Oil paints dry much differently than acrylics. Oils dry through a process of oxidation, where acrylics dry through a process of evaporation.
Oxidation is a process where the drying oil is absorbing oxygen to create a paint film, and it can take a week or more before the paint film won't smudge, and up to six months before the paint film is dry completely. This is typical of most oil paints.
Temperature and humidity can play a role related to how quickly the oil will absorb the surrounding oxygen, but generally speaking, the use of a heat gun or dryer won't have that much of an effect.
Acrylics dry through evaporation, a process of moisture from the paint being absorbed into the air, and this process allows for a paint film to form in a matter of minutes, with a permanent paint film forming between 24-72 hours.
You can use oils on an acrylic primed surface without issue, just not the other way around.
I hope this answers your question.
Met vriendelijke groet, With kind regards,
Marten Talens founded Royal Talens, the Dutch Factory for Paints, Lacquers and Inks, in Apeldoorn (the Netherlands) in 1899.