Filling Balsa with white glues????

The Rocketry Forum

Help Support The Rocketry Forum:

Fore Check

Well-Known Member
Joined
Sep 24, 2010
Messages
4,263
Reaction score
7
I've seen a couple of places that some use white glue to fill balsa with.

Could someone please post some details? Is it sandable and durable? How many coats does it generally take?

I'm looking to try something new. Sealing the balsa is the biggest whipping of building a rocket to me.
 

NUBlackshirts

Well-Known Member
Joined
Jun 3, 2003
Messages
313
Reaction score
0
I have done that on a few of my small rockets. It works ok. Seems to help with fin strength a bit. I usually do a couple of coats and then follow up with some Fill N' Finish later. Haven't had any problems so far.

I know some people use white glue to sandwich the fins with paper. I have not tried this though. From what I hear, it makes them pretty strong.
 

Johnnie

Well-Known Member
Joined
Dec 31, 2002
Messages
4,292
Reaction score
0
...be careful though as white glue (at least Elmers glue) tends to shrink to get it's strength, there by causing warpage. I warped a killer set of ESTES Sidewinder fins:mad:

CA or finishing epoxy fills and strengthens balsa fins and balsa nosecones.

Johnnie Paul
 

bsexton

Well-Known Member
Joined
Jan 18, 2009
Messages
1,085
Reaction score
1
Anytime you get balsa "wet" it will warp so you need to be careful with whatever method you use.

I believe Peter Alway uses the white/yellow glue technique for filling and strengthening balsa fins. I used this for the first time on an Estes Bull Pup and it worked OK. I only applied one coat of yellow glue and used a plastic spatula to smooth it out and scrape off the excess.

You can also try applying Japanese tissue or silkspan with Butyrate Dope which has one of the best strength to weight ratios.

Also, there are many posts about applying white/yellow glue and copy paper - OR - spray adhesive and Avery labels to balsa fins for added strength.

I just used dope/silkspan on the fins for my Estes Fat Boy and I am experimenting with the copy paper idea on my Estes Big Daddy.

Bottom line, there are many techniques and opinions for finishing balsa fins - experiment and pick the best method for you and your rockets.
 

Vance in AK

Well-Known Member
Joined
Jan 6, 2003
Messages
188
Reaction score
0
I used normal copy paper & spray adhesive to laminate the fins on my Gemini DC. I cut the paper slightly larger than the fins, applied the adhesive to one side of the fin, applied paper to that side & smoothed, immediately repeated on other side of fin.
Did all four fins & then sandwiched them between two layers of glass with weight on top to make sure nothing warped or bubbled. Next day trimmed excess paper from edges, and sanded edges.
Takes paint very well, with a very smoothe finish. No need to fill before laminating.
I couldn't believe the strength difference.
My Gemini DC is converted to a standard single chute with forward ejection. Last launch their was a nose cone seperation at ejection, & the chute went with the cone.
The rest of the rocket came in from C6-3 altitude at max velocity. It landed tail first, mostly on the tip of one fin on a packed gravel road. Not pavement, but close. The only damage was a rounding over of about 1/8th" of that one fin. I believe without the paper lams that fin & probably one or two others would have been history.
I'm a believer.
That's the next step on my Super Big Bertha.
Vance in AK.
 

astronboy

Well-Known Member
Joined
Sep 11, 2002
Messages
2,618
Reaction score
0
I am in the finishing stages of an ESTES Sprint clone. I sanded the fins to a very fine double airfoil, and am using the yellow glue technique for stregth:

I apply the glue using an old credit card (I maxed it buying rockets anyway!!) and I really force the glue into the wood pores, leaving only a thinnest coat on the surface. Once this has dries overnight, I sand with 400 grit wet/dry and apply a second coat. After another overnight dry and a good sanding I apply several coats of primer paint, and I am good to go.

I have found that yellow glue sands a bit better than white glue.
 

sandman

Well-Known Member
Joined
Jan 18, 2009
Messages
10,563
Reaction score
6
I have heard a lot of people have a warpage problem.

I don't because I always wait until the fins are installed and fillets are finished.

Then I just blend it into the fillet.

I use Fill 'n Finish after the glue dries.

I find if I don't at least do a coating of glue, the balsa just seams to soak up most of the primers.

Sorta like a "primer" for the primer!

Pre-primer???:confused:

eh...it works for me!

sandman
 

Vance in AK

Well-Known Member
Joined
Jan 6, 2003
Messages
188
Reaction score
0
Sandman, I know you've been at this for years, & I assume you've tried the laminated paper over balsa fin thing. What did you think of it?
On the remote chance you haven't tried it, I humbly suggest you give it a shot on some scraps & see what you think of the finish & strength increase.
Vance in Ak.
 

Juerg

Well-Known Member
Joined
Jan 30, 2012
Messages
183
Reaction score
11
For fins I suggest you try this:
Get some very light glas cloth (like 40g/m2)
Paint the fin with epoxy, apply the glas cloth on both sides.
I am using two metal plates to compress the fins between two plastic foils (don't forget the plastic or you will never get your fins out ;) )
You will get a perfect surface that needs little if any sanding and a fin that has gained in strength incredibly!
And it will be lighter than a fin finished with filler!

For nose cones and transitions I am using a similar method:
Apply a VERY light coat of spray glue to a pice of your glas cloth, just enough to get a slightly sticky surface. Then apply the glas cloth to the balsa part, cutting it to pieces where necessary.
Once the whole part is covered by a layer of glas without wrinkles, simply paint the part with laminating epoxy and let it cure.
After the epoxy has cured you will just need some light sanding to get a perfect and hard surface.

Juerg
 

sandman

Well-Known Member
Joined
Jan 18, 2009
Messages
10,563
Reaction score
6
Vance,

I have tried the paper technique...it's all right but not my "cup a tea".

Actually I prefer not to "fill" the grain. I don't mind the fact that you can tell it's "made of balsa".

I use the Elmer's to "sorta" fill the grain, add some strength and to seal the wood for painting.

Quick and dirty.

Am I strange or what?

sandman
 

powderburner

Well-Known Member
Joined
Jan 18, 2009
Messages
7,400
Reaction score
5
The biggest problem I have had with using white glue for filler is that the paint color coats craze badly if you spray them right on top.

You have to do a little sanding (a problem in itself with white glue, it doesn't like to be sanded) and use a primer coat, or your nice paint job will only last a few weeks.
 

sandman

Well-Known Member
Joined
Jan 18, 2009
Messages
10,563
Reaction score
6
I only use enough glue to soak in. A thin layer.

Sanding is easy...I just knock the bumps off (the knap of the wood comes up a bit) with some 220 grit.

I always prime!

sandman
 

Vance in AK

Well-Known Member
Joined
Jan 6, 2003
Messages
188
Reaction score
0
Sandman.
I too kind of like the look of painted but unfilled balsa when there is just a bit of grain.
To me the advantage of the paper is the added strength. After the Gemini DC flight I mentioned earlier I'm a believer.
If we all liked the "same cup a tea", I guess that flavor would be all gone!;)
Vance in Ak.
 

bsexton

Well-Known Member
Joined
Jan 18, 2009
Messages
1,085
Reaction score
1
Originally posted by sandman
...Actually I prefer not to "fill" the grain. I don't mind the fact that you can tell it's "made of balsa".

I use the Elmer's to "sorta" fill the grain, add some strength and to seal the wood for painting.

Quick and dirty.

Am I strange or what?

sandman
Oh my goodness -- next thing you are going to tell us is that you don't fill the spirals in the body tube either... :eek:
 

sandman

Well-Known Member
Joined
Jan 18, 2009
Messages
10,563
Reaction score
6
Actually it depends.

A scale job yes, I fill the spirals. A classic clone, probably not.

My Astron Spaceplane is painted with just two coats of Cub Yellow butrate dope.

sandman
 

bsexton

Well-Known Member
Joined
Jan 18, 2009
Messages
1,085
Reaction score
1
You know I'm just jerking your chain.;)

Back in the "olden days" there was no such thing as spray paint. Every rocket I owned was painted by brush with dope -- those were the days!
 

Mike

Well-Known Member
Joined
Jun 3, 2011
Messages
1,330
Reaction score
0
Thinking about it I tend not to fill fins or spirals either. Occasionally I will stengthen a fin, but what I usually do is put a few coats of primer on so that it has that 'glossy balsa' look.

As for filling spirals I've never even tried. If I were building a high power bird with an obvious spiral or scale then I geuss I would but low power tubes I tend not to even notice the spiral, just my eye I geuss.
 

NUBlackshirts

Well-Known Member
Joined
Jun 3, 2003
Messages
313
Reaction score
0
Well, I decided to try the paper laminating technique for my Silver Comet. So far it seems to be going well. One fin messed up a little bit when I got impatient and didn't wait for it to dry completely. No warping, just the paper tore a bit. I took it off and put a new piece on. The fins definitely seem much stronger now. I figured this would be a good rocket to try this on since the fins are kinda large. Now to start cutting the boattail.....
 

TwoWalks

Well-Known Member
Joined
Dec 1, 2003
Messages
128
Reaction score
0
Originally posted by Mike
Thinking about it I tend not to fill fins or spirals either. Occasionally I will stengthen a fin,

As for filling spirals I've never even tried.
Mike at the current time I am in agreement with your way of doing it. I am new, most of my Rockets are not going to be flawless for a while. Then there is the crash landings, the floating out of site and not found ... I think the list goes on and on. For now, I am focusing on Build, Paint, Fire. :)
 
Top