For example, if you had a matt black and you needed gloss black just use matt black and a top coat of gloss varnish. Likewise you could turn a gloss colour to matt with a top coat of matt varnish. Does the still apply today. Why do I ask? Well 2 reasons. 1) I need a matt orange for some chaff dispensers. Im trying to use humbrol where possible and I own a gloss orange (no 18). In matt they do an Orange Lining which doesnt appear an exact shade match. Could I just use the Gloss I already own and apply a matt varnish over the top. 2) Its the old Airbrush thing. Im getting on really well with acrylics now. I need a Glossy Grey (no. 5) whch again is not available in Acrylic, only enamel. Could I get the matt acrylic equiv. ad spray a top coat of gloss varnish? If the varnish trick works do I thin i the usual way. I thin down with water on a 2:1 basis as per humbrol instructions and getting on very well. In fact what I actually do is tip the paint from the plactic pot (12ml) into a new glass jar. Add 6ml water to the plastic pot and give it a damn good shake and then add that to the jar. (Being a hoarder I then wash out and keep the plastic pot, to use for mixing paints later). I then give the jar a damn good shake (I usually do this while watching TV and I find if I shake for the entire length of an advert break it works for me), label up the jar and pop away ready for use when I need it. I find that 6ml if water added to 12ml of paint doubles the volume of paint (Its the old tonne of feathers and tonne of lead thing) and works for 99.99% of the paint. Anyway, waffling now Can I use varnish to change the finish of a paint. Do I thin varnish down for airbrush use in the same way as normal paint.