"Dry Rubbing" Balsa

Someone in another thread had asked about "Dry Rubbing" balsa fins, so I am making a post here. The process consists of rubbing a paste type filler into the balsa to fill the porous wood before finishing. The method works well and produces a real nice paintable finish without having to deal with liquid or high fume fillers.

Here's the process: https://www.rocketryforum.com/ctulanko/album/index.php?dir=dryrub

Carl

Thanks for taking the time to share this process in words and pictures. I'll give it a try!

Keith

I have been using Elmer's Fill n Finish lightweight that comes in cans. I'm going to try this stuff Carl is using, it looks easier to deal with.



Scott

Thats a real good idea!

Looks as if thats the new Estes Patriot.....I just built one with a 24mm....I will try the dry rubbing

Just tried the "rub" method on my latest creationl, it worked great! Thanks for sharing that tip.

Keith

The problem that I find with fill and finish is the waterbased nature of it. I've used it to fill tube seams and fins and even when you glass over them. On a Hot day, the moisture that is trapped in the product will cause the material to bulge, I can take a rocket that the seams were filled with the elmers product and show you where every seam is as it will raise up in the heat and even show thru the fiberglass wrap. ...

I've gone to Bondo glazing putty for now to avoid this problem.

Alan

Originally posted by aadamson
I've gone to Bondo glazing putty for now to avoid this problem.

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I use a lot of Bondo glazing putty as well, just hate that my finger turns red!

Here's some samples of it in use here

I like it if for plastic nose cone seams too!

Nick

I use the bondo putty also..I don't fill fins with it ..but it does very well on spirals.. and does real nice on further smoothing the joint from fillets with yellow/white glue and as Nick mentions the nose cone seams

the only drawback (if it really matters)
is it is somewhat heavy ,and not compatable with epoxy...

I have glassed over it, and haven't noticed any problems with loss of adhesion so far
so the compatability issue might not be much of a problem

I'm planning on trying the dry rub technique also

Just to make things interesting, let's toss this into the mix. I've just dry rubbed it on my Drake (I'm a finishing procrastinator) and sanded and it seems nice. Let you know when it's primered. Got it at HobbyTown..

FWIW,
-bill

I use this "dry rubbing" method to finish all of my fins, and it works great!

I have not noticed the "bulging" associated with a temperature increase, but I take an additional step.

Before finish sanding, I place my fins in a stackable dehydrator on high setting for 3 hours. This ensures that the paste is completely dry and minimizes and/or eliminates any warping caused by the application of the "wet" paste. Works like a champ!

Cheers!

where can I buy this stuff. does it take glue well?

Fore Check said:

I use this "dry rubbing" method to finish all of my fins, and it works great!

I have not noticed the "bulging" associated with a temperature increase, but I take an additional step.

Before finish sanding, I place my fins in a stackable dehydrator on high setting for 3 hours. This ensures that the paste is completely dry and minimizes and/or eliminates any warping caused by the application of the "wet" paste. Works like a champ!

Cheers!

Click to expand...

My, oh my how things change. I posted that over 4 years ago. If you asked me about this finishing technique today, I simply won't do it anymore (and haven't for a long time.)

It's messy, it's time consuming, and there is a higher risk of fin warping. It's very difficult to dry rub fins that are already attached to a rocket.

There are plenty of methods for filling balsa grain. I prefer aerosol sanding sealer. Other folks have their preference. I'm just chiming in since this thread re-appeared to say that experience has dropped dry-rubbing to the bottom of my list.

oh k i guess i'll keep with the sanding sealer i use then. thanks.

as for things poppin upwhat can say blame the search program.

Carl, the link isn't working for me this morning.

CharlaineC said:

as for things poppin upwhat can say blame the search program.

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LOL,

Kinda cool to read where I was when I started using this forum. Like a blast from the past.

CharlaineC said:

oh k i guess i'll keep with the sanding sealer i use then. thanks.

as for things poppin upwhat can say blame the search program.

Click to expand...

Charlaine:
Instead of "sanding sealer" have you tried "Balsa Filler number 70. Used to be Pactra, now manufactured by Midwest or something like that. Both are still "dopes" which are lighter weight finished paint films. but the Balsa Filler uses larger and more talc solids so they fill the grain in far fewer coats.
I only use the stuff occasionally, As I prefur to just shoot bare open grain balsa or basswood with sandable Primers then use any of the fillers at all. If you have tried this stuff, it's worth a look Man Your bringing back a lot of 3 and 4 year old threadsLOL!

Aerogloss does a fine job filling balsa, so does the microfill paste..But, beware, the aerogloss stinks to high heaven-guess thats why they call it 'dope'..If you use it too long in an enclosed space you will get 'dopey'...dont ask me how I know!