I think Superfil is easier to sand and is more consistent than microballoons. Each batch of microballoons is likely to vary in the proportion of balloons to resin and how evenly it’s mixed. The filler turns out harder or softer as a result. Mixing Superfil by weight means the components are always the same. Based only on sanding/shaping effort, my impression is that micro is stronger than Superfil.

 

However, I think it’s best to use the stuff fresh. Maybe there’s variation in the batches but out of three 3-gallon kits used so far one stayed put until cured, similar to a dry microballoon mix, and the others tended to slump and slide. I tend to have the stuff around for a year or more so maybe it’s a shelf life issue. OTOH the liquidity seems to allow the Superfil to penetrate the underlying surface for a good bond.

 

  What I’m doing is to use a microballoon slurry as a bonding coat for bare surfaces then putting very dry micro on top before the slurry sets. This allows me to build up areas as needed and the dryer micro is easier to sand. After rough sanding I use a thin layer of Superfil. If a surface is very even to begin with I’d go straight to the Superfil.

 

I think this is a good approach but what counts is when the surfaces flex in flight. I haven’t got to that point yet.  -Bill Wade

Has anyone used superfil rather than the micro slurry for body work?  I've done the microslurry on my Lancair and am looking for a comparison and whether superfil is any easier to sand than micro?  Thanks.    Don G.