Pip Seymour’s refined linseed oil in unbleached. This is the colour that bleached oil turns to over time – we decided not to bleach the oil, so that the end user knows that this type of product has this n-built defect. In any case, adding any linseed oil to oil paint tends to cause darkening/yellowing over time.
The best use for this type of oil is in painting grounds – to make half oil grounds with whiting, titanium white and rabbit glue (as emulsion). There are recipes for such in The Artist’s Handbook.
It is also good with egg to make a tempera grasse – egg-oil emulsion.
For paint making with pigment, cold pressed oil (flax oil) is preferred as it changes less over time.
If adding oil to oil colour, it is technically better to add a mix of stand oil-turps 50/50, to the same consistency as linseed oil – this mix darkens less than refined linseed oil.