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-   -   Sanding Sealer Process Questions (http://www.oldrocketforum.com/showthread.php?t=8179)

GregGleason 12-03-2010 11:53 AM

Sanding Sealer Process Questions
 
I recently got some Deft sanding sealer (must be GREAT stuff, since it is so ... so ... uh ... aromatic) and put it on some pine.

Two of my sons are cub scouts and are going to put their cars in the January Pinewood Derby.

My questions are:

1) How many coats
2) Do you sand between the coats, or do you sand after multiple-coat applications
3) Do you primer over the sanding sealer or straight to paint (my guess is primer it)

I know this is a basic question but it has been decades since I last used sanding sealer and I wanted to get a sense of the prevailing conventional wisdom.

I know that pine is not balsa, but my guess is that for this phase, you would treat balsa the same as pine (since it is a fairly soft wood).

Greg

jeffyjeep 12-03-2010 11:57 AM

I think 4 coats should be good. Sand with 320 after each coat. Sand with 400 after the last coat. Tack cloth, primer and paint.

Please post photos!

p.s. I hope they win!

ghrocketman 12-03-2010 12:48 PM

I doubt you will need four coats.
Pine is about the hardness of Basswood which rarely needs more than 2 coats, 3 max.
Sand between each coat.
Paint may be applied directly over the Sealer for an acceptable finish, but will look better if primed first.

jeffyjeep 12-03-2010 01:17 PM

2 Attachment(s)
GH is probably right. I've never finished pine with sanding sealer, but it IS a denser wood, so probably only 3 coats. As far as primering: personally I primer EVERYTHING. That's just how I roll. I use white primer under everything except black, and gray primer under black.

I still have my old PWD car. It had a windshield long ago. It was slower than a retarded clam, but it sure was pretty!

ghrocketman 12-03-2010 01:45 PM

+1 to what jeffyjeep said about primer.
White under everything BUT black.
For black I use DARK grey (sometimes called hot-rod black) primer.

Incidentally, I NEVER use Balsa Fillercoat prior to Sanding Sealer for any woods but BALSA.
It is a waste.
For Basswood, Aircraft Ply (Spruce), or Lite-Ply (Poplar), I finish ONLY with 1-3 coats of Sanding Sealer depending on what the grain requires.
For balsa, I use 3-4 coats of Fillercoat with sanding between coats 2, 3, and 4 prior to 2-3 coats of Sanding Sealer.

Added Tip: anyone who uses Sanding Sealer prior to Balsa Fillercoat for finishing balsa is doing it BACKWARDS. The Fillercoat should ALWAYS be applied prior to the Sealer to fill the grain, whereas the Sealer provides a smooth plasticized topcoat for the primer/color coats.

jspitza 12-03-2010 02:44 PM

GH Rocketman:
Even SIG sanding sealer is not the first step? Hobby lobby sells this right by the pinewood derby section. That stuff is so thick, I thought its supposed to fill the grain first then use whatever to provide the surface gloss. Also, does dope based products eat wood glue joints? Also, is SIG or any other clear dope even needed in rocketry? I've tried delta creamcoat and fnf: personally I don't like either one and the aerogloss blows em away but that dam smell............. Good luck with your pinewood derby cars!!!!! I'll be cheering(virtually that is) Take care, Jeff

scigs30 12-04-2010 08:54 AM

Quote:
Originally Posted by ghrocketman
+1 to what jeffyjeep said about primer.
White under everything BUT black.
For black I use DARK grey (sometimes called hot-rod black) primer.

Incidentally, I NEVER use Balsa Fillercoat prior to Sanding Sealer for any woods but BALSA.
It is a waste.
For Basswood, Aircraft Ply (Spruce), or Lite-Ply (Poplar), I finish ONLY with 1-3 coats of Sanding Sealer depending on what the grain requires.
For balsa, I use 3-4 coats of Fillercoat with sanding between coats 2, 3, and 4 prior to 2-3 coats of Sanding Sealer.

Added Tip: anyone who uses Sanding Sealer prior to Balsa Fillercoat for finishing balsa is doing it BACKWARDS. The Fillercoat should ALWAYS be applied prior to the Sealer to fill the grain, whereas the Sealer provides a smooth plasticized topcoat for the primer/color coats.

I must be doing it BACKWARDS because I never use Balsa Fillercoat, just 3 to 4 coats of balsa sealer for smooth balsa fins. 3 to 4 coats of balsa sealer sounds less than 3 to 4 coats of balsa fillercoat followed by another 2 to 3 coats of balsa sealer. Someone else on another forum told me I was doing it wrong also but I think the results speak for themselves. Feel free to search my builds and I think my balsa parts come pretty good for doing it backwards.
The Vigalante has 3 coats of balsa sealer

Centuri Screaming Eagle clone 4 coats of balsa sealer

Avenger 3 coats of balsa sealer

jeffyjeep 12-04-2010 09:22 AM

Beautiful work! I don't use ANY filler coat either--just sanding sealer.

GregGleason 12-04-2010 12:27 PM

Very nice work scigs30!

Thanks for posting them.

Speaking of posting, I'll try to get some pics of the process.

Craftsmanship seems to be a never ending process. :o

I'll likely toss them in the Projects area.

Greg

jeffyjeep 12-04-2010 12:50 PM

True. I hate to sound esoteric, but craftsmanship IS a journey without end.


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