CA'ing Balsa

I have, like a lot of folks, been using CA glue to sort of harden balsa to make it easier to prep for paint. I've basically, just squeezed some onto the wood and smeared it around. But this seems like it just "case-hardens" the balsa. I hear people talking about "soaking" in CA, so I wonder if there's a different (better) technique.

Here's where I'm going with this: when I built Binary Star (https://www.rocketryforum.com/showthread.php?122619-Binary-Star&highlight=binary+star), I had issues with the survive-ability of the tips of the longish, conical nose cones. I wasn't CA coating the wood back then. I broke one tip just because I knocked the rocket over while building it. I was able to glue the tip back on, add so filler, and moved on. The second cone got broken when the wind knocked it off of my prep table at LDRS34. I wound up cutting the top 1/2" off of both cones, leaving them squared off. It has a different look than the original intent, but its still kind of neat. Since, I've built a BT60-sized Nike Smoke, this time CA'ing the whole upper half of the cone. It hasn't broken yet, but I'm nervous about it.

Now, I'm starting a BT60-sized Black Brant III, which will use an 8" long conical nose cone from Semroc. The cone just arrived yesterday, and its length and needly point make it quite fine at the tip (I'll have to get a picture later). Its kind of impressive to look at, since the tip's included angle works out to about 12 degrees. Now, to be more scale-like I will blunt it slightly, but it'll still have a long, skinny tip. I'd like to protect it from potential damage as much as possible. What's the best way to do that, short of a glass wrap?

The super thin CA would probably work fine, but you might also get good results with a slow curing finishing Epoxy like Bob Smith 20 or 30 minute.

The thinner epoxies tend to soak/absorb into the balsa nicely.

Thin CA will wick in nicely. Our kids had a nose cone on one of their TARC rockets that kept getting dented, so they eventually rebuilt the tip using automotive body filler and it lasted a long time.

You might try a little of both... Super Thin CA the actual tip, then try the slow cure Epoxy over that. I've been hearing some positive things about the epoxy and its ability to protect against dents, but I've yet to see one that can wick into balsa like the CA does.

One thing that I can think of that would help with the epoxy, is if you can figure a way of putting it on a "rotisserie" to keep it from sagging or running while it sets up. With that you might be able to save a ton of sanding.

And for those who aren't familiar with how to apply CA to a nosecone, I'll toss a link to my tutorial here.

I have a long thin, fragile balsa nose cone. Should I use sanding sealer first on the nose cone, or just use the thin CA on it?

Well, that's the heart of that matter, the exact question I'm asking in starting this thread. I'd say that sanding sealer would close off the pores of the wood and prevent the CA from penetrating. My question is whether or not having the CA penetrate in actually adds strength, or if it just would make it brittle. This is the cone I'm concerned with (the upper one, obviously):



If we're talking about coating with glue or epoxy, has anyone given any thought to papering? What I've read regarding fins, the glue alone doesn't add strength, that it needs some sort of matrix to bond to. Won't that also apply here? It seems like that (at least for a straight conical shape) making a paper taper wrap ought to be easy enough.

EXPjawa said:

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(in best Paul Hogan voice): "Now *that's* a nose cone"

If we're talking about coating with glue or epoxy, has anyone given any thought to papering? What I've read regarding fins, the glue alone doesn't add strength, that it needs some sort of matrix to bond to. Won't that also apply here? It seems like that (at least for a straight conical shape) making a paper taper wrap ought to be easy enough.

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I asked this question once. The answer was... well, maybe. I never tried it. I think that going all the way to the tip would be very challenging, but you could go to within 1/2" or so and then use epoxy or CA to strengthen the tip.

K'Tesh said:

I've been hearing some positive things about the epoxy and its ability to protect against dents, but I've yet to see one that can wick into balsa like the CA does.

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I don't know about the wicking (although I would think 30 minute epoxy would grab in pretty well) but it sure does create a hard, glass-smooth surface.

To me, the toughest part would be applying a very thin, even layer of the stuff, and then the question is how thick does it need to be to add sufficient strengh. Maybe a rotisserie would help, but I dunno if that's the whole answer.

I haven't been too happy with my nose cone CA experience so far, so I'm still in search of alternatives.

I know from experience that the thin CA from Hobby Lobby (pink label) will wick through a nose cone and glue your fingers to the shoulder.... (wear gloves)
As for how much good it does, I am not sure. I know that I have a few that I did not CA with and Estes Smile now, while all that I have CA'd never seem to get one.

I have some super thin epoxy that is made for sealing concrete that soaks into plywood. I am up to 3 coats on the bottom of my boat and it is still soaking in.... I do not know how far it penetrates, I am just trying to waterproof the outer shell of the boat. Unfortunately the smallest kit is a gallon https://www.ebay.com/itm/MARINE-GRA...090356?hash=item35b8b44bf4:g:TqMAAMXQySpRMwQ0

Soaking thin CA works very well to toughen balsa and other porous woods. I've turned pens on a lathe from spalted oak and spalted maple by saturating with CA. Spalted woods have streaks of discoloration, typically black, from fungus. Pieces can often be quite soft, and even crumble if squeezed or roughly handled. The CA will toughen enough to turn with sharp lathe chisels. Sometimes additional applications are needed when the diameter is reduced and wood is exposed that was not saturated by the CA.

For finishing, CA is so hard that it can be finely sanded and polished to an incredibly glossy appearance. What helps is the pen blank spinning at 1000s of RPMs while sanding and polishing! That level of smoothness would be tough on fins, but they can be sanded sufficiently to prime and paint with excellent results.

I would like to hear more about this papering a balsa nose cone idea...

The_Lone_Beagle said:

I have a long thin, fragile balsa nose cone. Should I use sanding sealer first on the nose cone, or just use the thin CA on it?

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You can just CA that fragile tip. I did this on the leading edge of fins on an Estes Phoenix. I had used a razor plane to shave a sharp aitfoiled leading edge, and it was really thin at the very edge. Soaking just the edges with CA worked well. I used sanding sealer on the rest of the fin.

I actually had just started an experiment with several balsa nose cones, and will try to continue.

My previous experience with using CA on balsa nose cones instead of sanding sealer was...ok/pretty good. They were small nose cones, and there seemed to be some unevenness of uptake of the CA. I was interested in using sanding sealer first just to see if it would help limit the uptake of the CA to just the outer layer, and maybe be more even?

The limiting factor is my lack of using something to spread the CA that won't stick to the darn nose cone (I had some close calls with gluing bits of my nitrile glove to the darn nose cone).

Any suggestions on some sort of metal tool to aid in spreading the CA? I guess ideally, I would have a vat of CA and would just dip the cone in tip first, and let it hang dry, but, that would be a lot of CA...

Using the lathe to polish it sounds like a great idea. Maybe after the divorce is finalized, LOL!

I've always just used the tip of the CA bottle to spread it around.

On just about any balsa or basswood part (nosecone or transition) I wick in Thin CA into the tip (about 1/3) first , then use a paper towel mop to spread medium CA over the reminder of the part.
Once cured (without accelerator) sanding with 220 to knock off any high spots some times another coat is used to fill any deep grain or fingernail gouges, dents etc.
when this is cured, the surface is sanded with 340-360 grit until smooth. then a coat or two of cheapy grey primer is all that needed to get a babies butt smooth finish.

On one of these threads a year or so ago someone was talking about their experiments with hooking a shop vac up to the shoulder to suck the hardener into the cone. Can't remember which hardener was being used, but I remember that it worked, but needed to be careful about gluing the vacuum to the cone.

kyle said:

On one of these threads a year or so ago someone was talking about their experiments with hooking a shop vac up to the shoulder to suck the hardener into the cone. Can't remember which hardener was being used, but I remember that it worked, but needed to be careful about gluing the vacuum to the cone.

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A bit simpler way I've found that works well with just about any size MODEL Rocket part is to mount the Cone or Transition on a 1/4" hardwood dowel, chuck it up in your variable speed hand drill and spin the part while holding a medium CA soaked Paper towel against the part. Applying a bit of pressure as the part spins forces the CA into the wood while it smooths and polishes the surface. Works very will on Cones micro T2+ to BT-80 size.

Micromeister said:

A bit simpler way I've found that works well with just about any size MODEL Rocket part is to mount the Cone or Transition on a 1/4" hardwood dowel, chuck it up in your variable speed hand drill and spin the part while holding a medium CA soaked Paper towel against the part. Applying a bit of pressure as the part spins forces the CA into the wood while it smooths and polishes the surface. Works very will on Cones micro T2+ to BT-80 size.

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That's an interesting approach. Just curious, how do you (safely) soak a paper towel with CA and hold it? Are rubber gloves satisfactory for that?

neil_w said:

That's an interesting approach. Just curious, how do you (safely) soak a paper towel with CA and hold it? Are rubber gloves satisfactory for that?

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This technique is popular when turning pens on a lathe, and so it will work well on balsa parts.

First, wear safety glasses or facemask! You don't want CA to get in your eyes, and this can easily happen if you use a bit too much and it gets flung off the spinning pen blank, Or in this case, nose cone.

Second, use nitrile gloves. You can get them at any hardware store or big box store like Home Depot. I buy them at Harbor Freight. A box of 100, often on sale, are under $10. Or use their coupons, found in lots of magazines.

You want to use paper towels since they will tear if wrapped around a spinning object on drill or lathe. Anything else is risky and you could be injured if fingers get caught in a rag wrapped around your nose cone. .

Tear a small strip, fold it over, and apply a few drops to it while bringing it in contact with your nose cone. It will get hot, so be wary of that. Move the pale towel around. As the CA cures, it can stick to the paper towel, so let up. Once dry, it can be polished. And more applications can be added repeated before final polishing to make sure the nose cone is well saturated.

Nose cozy

This won't strengthen it, but might be a consideration during transport, in storage, and even in flight if you might be landing on a hard surface

https://www.rocketryforum.com/showt...-Some-Helicopter-Recovery&highlight=Nose+cozy

neil_w said:

That's an interesting approach. Just curious, how do you (safely) soak a paper towel with CA and hold it? Are rubber gloves satisfactory for that?

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Safety Glasses are a must to protect the eyes. Face mask is totally unnecessary.
When I started this CA application process, I used to ware nitrile gloves but have learned that when using Medium CA with a quad folded 1/4sheet of paper towel the gloves are unnecessary as the CA doesn't penetrate all the way to your fingers. and it Heats Up the towel before soaking thru.
Generally I apply CA to an area of the towel about 3/4" square, only enough to start to saturate that part of the paper. Immediately start the drill while holding the CA wet towel against the surface. Even on the Largest Cones I have yet to have a paper towel "stick" to the cone while the cone is turning. When the paper towel mop startes to heat up it's time to fold and wet another piece. Generally even BT-70 size cones only require 3 or 4 mops.

I usually have a soldering exhaust fan pulling the CA fumes away during the process. a small fan blowing from behind will do the same thing.

Another thing I do before taking the cone or part out of the chuck is rough sand any high spots with 220-240 sandpaper. If this causes bare wood to be exposed another couple mop applications are applied and then further smoothed with 360-400 grit paper. Most of the time this isn't nesessary as the cone or transition will smooth up almost babies butt smooth with just the CA coating.

To say face mask is totally unnecessary is just absurd. Never rule out something that increases safety. I did not say one is mandatory and "totally unnecessary" is ridiculous. There are numerous instances of too much CA being used while applying it to wood being turned on a lathe. A facemask just gives an additional level of protection. Also, nitrile gloves are not just for keeping CA from sticking to fingers. The paper towel can get incredibly hot and the gloves insulate you. Regarding a paper towel sticking, it happens easily when doing fine wood turning. The smoother the surface becomes, the more likely the paper towel will start to stick as the CA heats up and begins to cure. On a rough balsa cone there is less chance of sticking.

Every serious wood turner has a face mask. If you have one, you ought to use it. If you are turning on a hand drill, maybe you don't have one. Fine, safety glasses are probably just fine.

Trident said:

To say face mask is totally unnecessary is just absurd. Never rule out something that increases safety. I did not say one is mandatory and "totally unnecessary" is ridiculous. There are numerous instances of too much CA being used while applying it to wood being turned on a lathe. A facemask just gives an additional level of protection. Also, nitrile gloves are not just for keeping CA from sticking to fingers. The paper towel can get incredibly hot and the gloves insulate you. Regarding a paper towel sticking, it happens easily when doing fine wood turning. The smoother the surface becomes, the more likely the paper towel will start to stick as the CA heats up and begins to cure. On a rough balsa cone there is less chance of sticking.

Every serious wood turner has a face mask. If you have one, you ought to use it. If you are turning on a hand drill, maybe you don't have one. Fine, safety glasses are probably just fine.

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Wow Lee just saw this post.... Lets unwrap your tightly wrapped Panties Nervous Nellie. You are the only one talking or even mentioning standing or sitting in front of a High speed Lathe where the wood part is spinning clockwise Parallel to the operators body. Well sure! If I'm using one of my Wood or Metal lathes I have Safety Glasses, Goggles, Full Face Shield, Projectile Resistant Vest, Acid Proof Full Apron, Sleeves and Gloves along with those nice Nitrile Gloves for those less costic turnings. BUT THAT IS NOT what we are talking about!
We are talking about using a standard very low to low speed (about 30-150rpm) cordless or corded 1/4" to 3/8" electric drill with the balsa part mounted slightly off center on a wood glue adheared 1/4" x 1-1/2" hardwood dowel. No matter how well we try to align a previously turned part that center hole is NOT going to be exactly centered which will cause the part to wobble as it is re-turned or in this case coated. Because of this Wobble VERY LOW speed is required. Our dowel is hand tightened in the keyless chuck, supported on a knee with the part projecting away for the body (8-12") rotating Perpendicular to our body. To throw any CA to the head or face one would have to be bending completely over the drill (not just impractical, it's just ever done). So I'll say again; the use of a full face mask is TOTALLY UNNECESSARY for this operation. Safety Glasses are all that is needed.

Again as I mentioned in the previous post, Using a quad folded 1/4 Paper towel, the towel heats up long before the CA ever penetrates to the finger telling one when to discard and use another piece. While the Nitrile gloves are nice they also decrease sensitivity to the heat making it possible to stick the towel mop to the glove. This doesn't happen often but with a little experience the glove can be eliminated and need not be involved. AGAIN we are NOT talking about LATHE turning! While using our low speed Drill the only time I've ever had or heard of a paper towel mop sticking to the part was when the drill was stopped before removing the mop for the part surface.

Shop safety is alway a concern. However overly restrictive "safety" measures are just as bad. Learn to read and understand a post before going off the deep end with overly harsh safety requirements that may keep other from trying a technique that doesn't need or require them. I'm surprised you didn't suggest the need for a flame proof covered trash container and fire extingusher....Good Grief!

John,

Hmmm, let's see ... Your fuming reply is twice as long as mine. You use bold, all caps in some places, underlined text, red text, and you think I've got tighty whities? Maybe time YOU took a chill pill. And since when is using a facemask an excessive safety measure, which is "just as bad"? More eye protection is bad? Give me a break.

Trident said:

John,

Hmmm, let's see ... Your fuming reply is twice as long as mine. You use bold, all caps in some places, underlined text, red text, and you think I've got tighty whities? Maybe time YOU took a chill pill. And since when is using a facemask an excessive safety measure, which is "just as bad"? More eye protection is bad? Give me a break.

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Try hard to stay on topic Lee!
Just cannot let such utter non-sense go without reply. Try hard to read & understand what is being presented before adding a bunch of crap that is just not necessary... your latest replay is just like your errant Lathe safety reply, UNNESESSARY! give yourself a break.

Micromeister said:

Try hard to stay on topic Lee!
Just cannot let such utter non-sense go without reply. Try hard to read & understand what is being presented before adding a bunch of crap that is just not necessary... your latest replay is just like your errant Lathe safety reply, UNNESESSARY! give yourself a break.

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I took your advice to give myself a break. Put you on my Ignore List. Life is too short to be distracted by insufferable blowhards with WAY too much self importance.