MITRA Forum Question Details

​Adding wax to oil paint has the opposite effect making paint 'short'. Additives such as wax and pigment stabilizers used in commercial artists paint make paint short. To make paint more flowing or 'long' add bodied oil (stand oil) to your paint. It does not need much to make paint longer. Adding excessive amounts of bodied oil, however, will increase the tackiness or drag of oil paint.

Some pigment extenders or fillers will not only extend paint but make ppaint longer. We found that pigment extenders with accicular particle shapes also tend to give paint 'long' behavior.

Liquin is not a filller but a medium. It would loosen up the paint but not make it long. I am guessing that What George is suggesting is not adding additional filler to a commercial paint, which would just stiffen it. Likely he means that paint made with certain additional materials made a longer paint. I have found that certain grinds of barium sulfate added to lead white make a very long and even ropy paint in linseed oil. Hand ground lead white in linseed oil will make a rather long paint unless the paint is made very lean.

If you want to use commercial oil paints that contain stabilizers like wax, castor wax, or aluminum stearate, your best bet is probably to add a bit of bodied oil or to grind up an appropriate filler in linseed oil (containing a proportion of bodied oil) to a rather loose consistency and add this to your commercial paint to the point where the paint behaves as you wish.

​You can start by adding a mixture of 3:1 refined or cold-pressed inseed oil and bodied linseed oil to your commercial oil paint, but you may also want to experiment with larger proportions of bodied oil to unbodied oil.

We have found extender pigments, such as wollastonite, which has an accicular partcile shape, useful also in giving paint a longer consistency. However, there are many extender pigments and color pigments that can be used, especially when the pigments have heterogenous particle sizes and shape (variety of size and shapes), such as is often found with paints made with natural earth pigments.

Oil paints that do not contain additives, such as castor wax, aluminum and magnesium stearates, tend to be longer, especially if the particle size and shape of the pigments are heterogenous.

What he said ;)

It is not simply about adding more oil when it comes to the rheology of paints BUT the addition of some oil/bodied oil can counteract the shortness induced by stabilizers (essentially materials added to tubed paints to keep the oil and pigment from separating) The prevention of oil separation is also the cause of shortness.