You can easily cover nail holes and blemishes in timber mouldings with wood filler. Push the filler into the hole, smooth it over, and lightly sand before applying your final finish. There is a wide range of readily available wood fillers that are tinted to suit the colour of the timber, which is ideal for staining purposes. Plain filler can be used if painting the timber. Useful Porta How To Video – Finishing Your Mouldings