Oil paint drying time tests

documenting the drying time tests for oil paints here

Questions
- why test for drying time
- when fast drying paint a good thing?
- when slow drying paint a good thing?
- pigment influence drying time - but so too does brand.


Method for setting up test.

- this is crappy, primed paper supposedly for oil painting but oil and water-based media soak right through to the back.  I hates this paper so it gets to be used for samples like  this.

- but as I am testing white paint, I put a layer of black gesso for that section.  That way I can see the paint.  I let dry about an hour before starting the test.  

- apply the paint in as even a layer as I can.  Using paint right from the tube with zero additives and making sure the brush starts dry each time to reduce contamination.  

- But how thick?  
as each paint has a different texture, and I have nothing that will measure in microns, I decided to use a criteria I could "see".  I apply the paint to the standard that most of it is opaque and I cannot see through the paint to the gesso layer in the middle two thirds.  I was imperfect at applying this standard, but it's at good enough for this experiment.  

- What does "dry" look like in measurable terms?  
I don't know.  Dry is different than curing.  I want to test "dry".  So the best thing I could come up with is to stick my finger in it and stick the finger beside it to see if paint comes off.  I'm using a firm rolling motion, but not rubbing or smudging.  

Did I miss anything?


Next post, the actual test and observations.  

From left to right:
Winton - Titanium white
Paul Rubens - Titanium white in Alkyd resin (fast drying version of their oil paints)
Winton - Ivory Black
Old Holland - Mars Black


My theory, the Winton paints will dry considerably faster than the supposed fast drying paints.  But it would be nice if I was wrong as almost nowhere has winton white or black in stock right now.  



Observations on day one.

I'm getting used to winton and this went on with very little elbow grease.  The white was a bit transparent, but a touch more paint did the trick for the most part (although I suspect it might become more transparent as it dries as it sometimes does that).  

Paul Rubens took about four or five times as much paint as winton white to get an opaque layer.  The paint was quite greasy and less pasty.  It also didn't have a fun texture to paint with, kind of sticky.  

Paul Rubens is a fairly new brand of paint (the other two have been making paint for over 100 years - old holland started in 1667).  I feel like Paul Rubens is still finding it's footing when it comes to paint making as they seem to adjust their formula every few years.  For this tube of paint, it felt very much like there was insufficient pigment to oil ratio.  

Old Holland is THICK paint.  It took very little to become opaque, but the paint was so thick right from the tube it was hard to spread around.  It took about 1/10th the amount of paint than winton and I think it could have used less if I had the ability to spread it more.  

Old Holland is one of the top, if not The Top fine arts oil paint maker in the world.  Their style is to pack it full of pigment to make as stiff a paint as possible.  That way we get as much pigment for our buck as we can and it's assumed that one will be using medium with this paint.  Medium would change the drying time significantly.  So I didn't go this path and instead stuck with right from the tube.  But I left a space for it just in case I want to try it later.  

Observation
- paul ruben white is getting close to dry. Too fast?
- using my finger wasn't the smartest choice as it's a pain to wash

at the two day mark, I declare the underpainting white by paul rubens dry enough to paint over.  



The Mars black could be painted over but would be safe with another day.

These are pretty much the reverse of my expectations.  

Day 4, I declare all are dry enough for painting a new layer.

Winton white was last to dry, I had expected it to be first.

That makes all these colours reasonable for underpainting (and possibly problematic for upper paint layers)



Winton also has a trouble when mixing as it easily forgets it was supposed to be white and gets overwhelmed by other colours.  I wonder if the pal rubens will be the same as it was quite transparent.   I'll have to try and find out.