is it possible to sand mr surfacer?
Yes, Mr Surfacer sands very easily and “feathers” nicely.
However, if you are using it to fill seams, you may find it easier to smooth/wipe off excess with a cotton bud or paper towel moistened with Isopropyl alcohol. No sanding required, no lost detail.
Yes, Mr. Surfacer does sand easily. I used Mr. Surfacer 1200 as a primer for my 1/48 P-40N and then sanded it a little with very fine grit. Resulted in a great primed surface and is also great for highlighting spots or areas that need a little more finishing work. As a lacquer based product, it dries fast so can be sanded soon after you apply it.