Applying Finishes to FUD/FXD parts- Part 1: Sealing Porosity
Porosity is a natural occurrence for FUD and FXD printed parts, FUD more so than FXD because of the coarser printing process. I have experimented with various ways of artificially filling, or sealing, the porous material to better accept a finish coat, from soaking the part in messy thin superglue (not recommended), to brushing on Testor's Glosscote to soaking in same with some reasonable success.
Mind you this is NOT an approach to filling in topographical surface imperfections from the printing process, but more an approach to avoid 6-8 coats of expensive topcoat. The only cure for that is sanding, sanding & more sanding...
Attempting this, you can watch with your eyes how the parts soak up liquids. It will take three to four coats before you will see that the part is fully saturated. It is difficult to predict how far the liquid will "reach" into the part, but it really doesn't matter, the goal is to fill the pores so the final coat can be applied with less paint overall.
Obviously this is an optional pre-finishing approach, but I tested it to see if there was any benefit, and there was reasonable impact; I was able to paint some parts with just two finish coats.
As an aside, The porosity tends to allow superglue to bond really well, especially between the remnants of a broken part so if you break a part bond it back together BEFORE you attempt to seal the part