when i cut my arches watercolour 300lb full imperial sheet into 4 pieces will the SAA 20x16 double mount aperture accept my paintings? According to the catalogue there is an aperture size difference between Daler Rowney and the SAA 20x16 cut outs.
what does 5mm offset on double mounts mean?

Hi Spangodrum! A Full Imperial sheet is, I think, around 22 x 30 inches, so cut into 4, each quarter would be about 15 x 11 inches. You'll obviously need to know the inside measurement of the SAA 20 x 16 double mounts, so thats the first thing to ascertain.

I think you'll find that the "5mm offset" on a double mount is the amount of "slip" showing on the mount. Sometimes this is a different but harmonious colour so that if the mount is, say, 20 x 16 outside size, there will be a 5mm "slip" showing around the inside of the mount, next to the painting. personally, I think double mounts, whether all the same colour, or with a different coloured slip, enhance a painting more than a single mount.

I hope this helps, but come back to me if you need any more clarification.

Very best wishes,

Steve Williams
PA & RSC Wigan area