How to make oil paint thick sticky and ropeyApproveRejectUn-ApproveSubscribeUn-Unsubscribe
Question asked 2017-06-02 14:48:33 ...
Most recent comment 2017-06-15 16:36:18
I have been trying to modify oil paint for textural effect and my goal is to make the paint thick sticky and ropey/ stringy. Auerbach sometimes seems to have gotten a similar paint quality where the rheology of the paint is highly thixotropic alla Lead White. I've also been thinking of the quality of silicon caulk as the texture I am after.
I have expeirmented with adding stand oil, dammar, clay made into paste, alkyd, etc but these tend to 'shorten' the oil, lowering the viscocity (with the exception of the clay). My next step is to see what marble or glass powder does. I have a (Daniel Smith) tube of transparent blender made with alumina hydrate that is perhaps the closest I've found for the texture I am after.
Any suggetions for this type if paint modification would be helpful.
Answers and Comments
You might get close to the results you describe by adding 10% by volume marble dust and some stand oil to factory-made titanium white. Blend on a glass slab until homogeneous, work with a glass muller, then introduce a small amount of stand oil with the knife. The resulting mixture will be long and ropy with distinct ribbons. (There is a PDF instructional on the Utrecht site with pictures. If the other Moderators don't object, I'll link it in a subsequent reply. There are no product links in the document.)
Matthew, you are welcome to post the link.
As to the question. The answer really depends on what paint you are
attempting to modify and exactly what handling properties you are searching
for. Most commercially available paints have added enough modifier (aluminum
stearate, castor wax, aluminum hydrate) to create a short buttery paint that is
similar in feel across the paint range. When modifying these you need to add enough
of the material (and likely extra oil) to surmount the action of the original
modifier. Matthew’s suggestion may work for what you want. I have made
handground lead white oil paint that was extremely ropey by admixing some
barium sulfate and a bit of extra linseed oil into the paint while I was
mulling it. The consistency was both dense and ropey at the same time.
If it were me, I would probably mull up a number of additives in oil to a
loose constancy and experiment with each of these by adding them to my white to
determine which created a paint with the rheological properties that most
closely resembled what I was searching for.
Please report back and let us know what worked for you.
Thanks, Brian. http://images.utrechtart.com/Content/pdf/experts_archive/studiocraft/Long_Bodied_Oil_Paint.pdf
Also, for artists reading this who don't yet know how to manually fill paint tubes, this is very useful when working in batches: http://images.utrechtart.com/Content/pdf/experts_archive/studiocraft/tubing_mixtures.pdf
In addition to the widespread use of stabilizers/amendments, I think the very small, uniform particle size of modern, precipitated pigments may also have something to do with the texture of today's factory-made whites, compared to what is seen on historical paintings. (Other Moderators will likely know more about this than I do.)
There is ample evidence that Dutch process stack lead white
paint behaves in its very characteristic manner due to the diverse, heterogeneous
morphology (as well as larger size) of the pigment particles as well as
its chemical reactivity with the oil medium. I know of two (periodically, three) manufacturers
who make old style lead white. It is interesting to experiment with these but
you may certainly find a paint that affords you the tactile and physical
effects you are looking for without resorting to such rarified materials; and I
mean no disrespect to those materials, I have stockpiled a substantial stash of
them just in case these manufactures stop production.
Also, Matthew, thaks for the tubing primer.
Most modern oil paints exhibit short
pseudoplastic flow (described as short, buttery paint) due not only
to the homogeneous particle size and shape of pigments, but also to
additives typically used in these paints.
Oil paints made from pigments of
heterogenous particle size and size exhibit different types of
viscoelastic flow. At Natural Pigments we have measured a wide
variety of pant behavior, including viscoelastic; time-dependent
viscosities, such as rheopectic (viscosity increases with duration of
stress) and thixotropic (viscosity decreases with duration of
stress); and non-Newtonian viscoelastic flows, such as shear
thickening (dilatant) (viscosity increases with increased stress) and
shear thinning (pseudoplastic) (viscosity decreases with increased
stress). Chemical and physical interactions between pigments and
drying oil gives rise to incredibly complex and often surprising behavior. Although additives are used in very small amounts in professional-grade oil paint—usually
less than 2% by weight of the pigment—their effect on flow is dramatic since the additives are adsorbed to the surfaces of pigment
Bodied (partially polymerized) drying
oils impart long flowing behavior to paint that is also described as
“sticky” or “tacky”. This is due to the large molecular
weight of polymers. Adding bodied oil to oil paint can often
accomplish what you are seeking. Grinding barite (barium sulfate) in
a blend of bodied oil and refined oil and then adding this mixture to
your paint is also useful and also does not thin the paint.
Basic lead carbonate (lead white) in
drying oils with low or no free fatty acid creates long, ropey paint.
Oils with free fatty acid, especially above an acid value of 4 or 5,
create the opposite. We have found highly variable paint flow from
lead white made according to the stack process or “old Dutch
method”. These paints exhibit different flows depending on the
particle size and crystalline forms of the pigment.
This Page Last Modified On: