Sanding Sealer Troubles

[Swampworks]

Using MinWax Sanding Sealer on balsa. I know I have used it before but lately I have been experiencing an aggravating occurence. The sealer is applied and left to cure at least a day but when I sand, it tends to flake off instead of sanding off. Almost like it is not penetrating into the grain. Anyone have any ideas about this? The balsa is not treated with anything prior to applying the sealer.

 

[Pat_B]

Is it possible that the balsa is totally saturated with the solution so that the excess solution is not curing properly?

 

[RangerStl]

I've used only Sig or Aerogloss dope-based products and have never heard of this problem. Are you using water-based Polyurethane or Butyrate Lacquer (dope) sealer?

I saw this question on another forum and seem to remember that you have the Poly?

Is this the first coat or a subsequent coat that is flaking off? Does it flake off leaving dry balsa or is the second-third coat failing to bond to the previous coat?

N

 

[Swampworks]

I've used only Sig or Aerogloss dope-based products and have never heard of this problem. Are you using water-based Polyurethane or Butyrate Lacquer (dope) sealer?

I saw this question on another forum and seem to remember that you have the Poly?

Is this the first coat or a subsequent coat that is flaking off? Does it flake off leaving dry balsa or is the second-third coat failing to bond to the previous coat?

N

As you noted, I am using the ployurethane version.....Will correct that in the future. It is the first coat that is giving me trouble, leaving bare balsa and once a spot flakes off, it just grows larger as I sand. Weird thing is that it doesn't happen 100% of the time. I have a nice sanded finish on the fins, but the nose and transition are giving me fits.

 

[hardinlw]

I've used Behlen lacquer sanding sealer with very good results. It's available in spray cans in woodworking supply places (Woodcraft for me). It dries quickly and builds well with little tendency to run unless you really load it on. I generally put on a couple of heavy coats, sanding between coats, and then let it dry a couple of days and hit it with an automotive primer. It's hard to tell when you have the grain filled with the clear sealer. The primer shows all defects and you can use the red lacquer putty (auto store) to fill any deep grain or the spiral groove. The key is to sand almost all of the sealer and filler off so that only the low spots are filled and you don't add a lot of weight.