I have recently returned to an oil painting that I started working on about two years ago and am extremely disappointed to find that the colours are lifting and smudging. Another problem I have is that my Rowney's turpentine goes sticky and dries on the pallet. Have you any words of advice?

The technical division of Daler-Rowney were mystified to hear about the lifting and smudging of the oil paints on your picture and say that the paint should certainly be dry after two years. They have told us that you are welcome to write or telephone them and they will discuss the problem in more detail. Their telephone number is 01344 424621. Regarding the problem with the turpentine, they say that unfortunately it will go sticky in time as the volatile components tend to evaporate. For that reason, it is advisable to make sure that the bottle top is securely on at all times.