Balsa nose cone treatment

How about a thin coat of finishing epoxy for a little extra ding resistance ?



This is the new nose cone for my Sirius Deimos (lawn dart documented here: https://www.rocketryforum.com/showthread.php?41087-Sirius-Rocketry-Deimos&highlight=deimos) Thanks, David !

I was rummaging through the paint locker and found some hobby shop polyester epoxy and mixed up a batch and brushed it on. Prior to this I sanded the raw balsa, one coat of Aerogloss fillercoat, and more sanding. I feel like I should get a tougher shell from this treatment without any weight penalty to speak of.

What'd y'all think ?

I`ve been using a 20 min.finishing epoxy on Balsa NCs for quite awhile and it works great.I also use it on big balsa fins and cardstock shrouds etc.


Paul T

I'm curious about benefits / trade offs of finishing epoxy versus CA for this kind of application. Is there much of a rationale to go one way or the other? I routinely hit cones with thin CA and sometimes a coat of medium or thick on top. Makes them quite hard but still sandable.

Always interested in these kinds of things!

How well does the finishing epoxy sand?

Does it go on pretty evenly?

How many coats do you have to put on?

I was considering this process too. It seems less messier than using CA.

The finishing epoxy not only adds some durability but also fills in most of the pores ,so it pulls double duty.Oh sure ,you may have to give it a smear of your favorite filler and a light sanding ,but it works.

The 20 min, finishing epoxy sands nicely and smells nice LOL

I mix it in a mixing cup and use a soft 1/2" brush and brush it on liberally and let cure for 24 hours.Multiple coats may be applied if needed.

You can/may and have even applied thin CA ,sand and apply finishing epoxy over that and sand smooth ,but filling those damn Balsa pores may still be needed !

Of course ,it`s like anything else in this hobby ,whether it`s sanding ,filling, decals or painting/primers......plenty of opinions and a million ways to skin a cat LOL


Paul T

So it will work well if you apply it over the balsa filler primer?

AfterBurners said:

So it will work well if you apply it over the balsa filler primer?

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Not sure Dan ,can`t see why it would not ,as long as the surface is dust free and wiped down with alcohol.

But I normally brush it on the raw ,sanded Balsa/plywood/Basswood first.

Works very well on the above mentioned wood surfaces.


Paul T

sodmeister said:

I`ve been using a 20 min.finishing epoxy on Balsa NCs for quite awhile and it works great.I also use it on big balsa fins and cardstock shrouds etc.


Paul T

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Thanks Paul. I've seen some of your build threads here and the results speak for themselves. If/when I get a TLP kit you better believe I'll be stea ...er copy ...er adapting your techniques.

Marc_G said:

I'm curious about benefits / trade offs of finishing epoxy versus CA for this kind of application. Is there much of a rationale to go one way or the other? I routinely hit cones with thin CA and sometimes a coat of medium or thick on top. Makes them quite hard but still sandable.

Always interested in these kinds of things!

Click to expand...

Yeah, probably just another way to skin a cat. Personal preference and availability of materials would come into play. For me, when I uncork thin CA it runs like mercury everywhere I don't want it to go. More of a reflection on the craftman than the tool, I think . And the smell ! Outside application is mandatory.

AfterBurners said:

How well does the finishing epoxy sand?

Does it go on pretty evenly?

How many coats do you have to put on?

I was considering this process too. It seems less messier than using CA.

Click to expand...

Well, I think the key to the first two questions is to start with a 20/30 minute epoxy. Get a good mix and flow it on without alot of extra brushing.

I'm planning on one coat; I'll sand with 320 or 400 grit then hit it with Rusto primer/filler and Bondo spot putty if needed.

samb said:

How about a thin coat of finishing epoxy for a little extra ding resistance ?

View attachment 117662

This is the new nose cone for my Sirius Deimos (lawn dart documented here: https://www.rocketryforum.com/showthread.php?41087-Sirius-Rocketry-Deimos&highlight=deimos) Thanks, David !

I was rummaging through the paint locker and found some hobby shop polyester epoxy and mixed up a batch and brushed it on. Prior to this I sanded the raw balsa, one coat of Aerogloss fillercoat, and more sanding. I feel like I should get a tougher shell from this treatment without any weight penalty to speak of.

What'd y'all think ?

Click to expand...

I used Aeropoxy ES6209 to coat Disappearing Act's nosecone, but it got bashed up on the lakebed anyway (before I went and lost it). It added no crush resistance, but it did help the scratch resistance.

Also, what's "polyester epoxy"?

sodmeister said:

The finishing epoxy not only adds some durability but also fills in most of the pores ,so it pulls double duty.Oh sure ,you may have to give it a smear of your favorite filler and a light sanding ,but it works.

The 20 min, finishing epoxy sands nicely and smells nice LOL

I mix it in a mixing cup and use a soft 1/2" brush and brush it on liberally and let cure for 24 hours.Multiple coats may be applied if needed.

You can/may and have even applied thin CA ,sand and apply finishing epoxy over that and sand smooth ,but filling those damn Balsa pores may still be needed !

Of course ,it`s like anything else in this hobby ,whether it`s sanding ,filling, decals or painting/primers......plenty of opinions and a million ways to skin a cat LOL


Paul T

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Sounds good I will give it a try. By the way I start from the tail, when I skin a cat. :y:

CarVac said:

I used Aeropoxy ES6209 to coat Disappearing Act's nosecone, but it got bashed up on the lakebed anyway (before I went and lost it). It added no crush resistance, but it did help the scratch resistance.

Also, what's "polyester epoxy"?

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Well scratch resistance will have to be good enough, I guess.

The bottle of stuff I used says "Low odor polyester resin" in the fine print (NHP Co. Shirley, MA. www.flashglue.com). From my limited research, I associate polyester with finishing epoxy which is "different" from adhesive epoxy. There are alot of folks on here with more experience with epoxies and fiberglass and high tech composite layups and I'll be happy to learn better. Heck, you might be one of those folks CarVac.

I`m thinking when a rocket comes in ballistic or very hard ,there is little that may be done to a nosecone Balsa/Basswood/plastics or even FG to prevent any type of major damage.

I suppose with wood fiber type nosecones ,there is solace in knowing that cracks ,dents and divots can be easily fixed.


Paul T

Marc_G said:

I'm curious about benefits / trade offs of finishing epoxy versus CA for this kind of application. Is there much of a rationale to go one way or the other? I routinely hit cones with thin CA and sometimes a coat of medium or thick on top. Makes them quite hard but still sandable.

Always interested in these kinds of things!

Click to expand...

I just use the Loctite CYA I get at Wal Mart. I would call it a medium CYA. I start with a bead around the base just above the shoulder. Then use swabs to spread it out. Then I hit the tip and work down. I can then sand it out without changing the shape of the cone. The bead around the base helps me level it to the tube after filling.

Polyester is just another type of resin as opposed to epoxy. It's generally cheaper, especially in large quantities, but the smell can be overpowering.

sodmeister said:

I`m thinking when a rocket comes in ballistic or very hard ,there is little that may be done to a nosecone Balsa/Basswood/plastics or even FG to prevent any type of major damage.

...

Paul T

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I didn't have any expectation of crash-proofing this thing . I think the folks way out west flying on those dry lakes have a different criteria for scratch and crash resistance.

HammerZ2008 said:

I just use the Loctite CYA I get at Wal Mart. I would call it a medium CYA. I start with a bead around the base just above the shoulder. Then use swabs to spread it out. Then I hit the tip and work down. I can then sand it out without changing the shape of the cone. The bead around the base helps me level it to the tube after filling.

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Thanks for sharing HammerZ2008. I'll try that technique sometime.

Pat_B said:

Polyester is just another type of resin as opposed to epoxy. It's generally cheaper, especially in large quantities, but the smell can be overpowering.

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Thanks. This whole area of two part adhesives is facinating with all the different formulas and additives.




22 hours later I have a pretty smooth shell and a bonus gnat that couldn't resist my warm garage with the intoxicating aroma.

samb said:

I didn't have any expectation of crash-proofing this thing . I think the folks way out west flying on those dry lakes have a different criteria for scratch and crash resistance.



Thanks for sharing HammerZ2008. I'll try that technique sometime.



Thanks. This whole area of two part adhesives is facinating with all the different formulas and additives.




22 hours later I have a pretty smooth shell and a bonus gnat that couldn't resist my warm garage with the intoxicating aroma.

View attachment 117739View attachment 117740

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Very nice ,and the Gnat makes it look like a piece of prehistoric amber..... nice touch ! LOL



Paul T

I'm definitely going to try this technique on my next build, but I'll try it on the fins and see how it works out. I was thinking about getting this stuff.

https://www.bsi-inc.com/Pages/hobby/epoxies.html

BSI has the 20 minute finish cure epoxy. I think would work as well right?

AfterBurners said:

I'm definitely going to try this technique on my next build, but I'll try it on the fins and see how it works out. I was thinking about getting this stuff.

https://www.bsi-inc.com/Pages/hobby/epoxies.html

BSI has the 20 minute finish cure epoxy. I think would work as well right?

Click to expand...

Dan ,

The BSI (and re-labelled by others) is the stuff I use.

If you want to re-use your brush ( I do ,because it`s a good quality soft bristle type) just soak and wash in alcohol.

I also do the same on my large plywood fins using West epoxy (the Hellfire and Arcas are two examples)



Paul T

sodmeister said:

Very nice ,and the Gnat makes it look like a piece of prehistoric amber..... nice touch ! LOL



Paul T

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I know, right ?!? It's almost a shame to cover up the little bugger. At least I'll have the photographic evidence.

I'm working on a cluster build soon, so I'll try it then.

sodmeister said:

Dan ,

The BSI (and re-labelled by others) is the stuff I use.

If you want to re-use your brush ( I do ,because it`s a good quality soft bristle type) just soak and wash in alcohol.

I also do the same on my large plywood fins using West epoxy (the Hellfire and Arcas are two examples)



Paul T

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AfterBurners said:

I'm working on a cluster build soon, so I'll try it then.

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sodmeister has alot of his construction and finishing tips on display in his build threads here. Well worth emulating I think.

I've used the West System 105/205 epoxy to coat a few balsa cones recently with really good results. Thin it a little with denatured alky and don't put too much on. It sands better than a lot of hobby-grade epoxies (BTW the get new 3M purple "pro grade" sandpaper, it will sand anything without loading up, I've been throwing out all my old stuff) and is really tough.

CA is a lot faster if you're in a hurry. One good coat of thin type (I use Zap in the 1 and 2 oz bottles), sand, follow with diluted spot putty filler, sand again. Perfect paint-ready balsa NC in 30 minutes.

caveduck said:

I've used the West System 105/205 epoxy to coat a few balsa cones recently with really good results. Thin it a little with denatured alky and don't put too much on. It sands better than a lot of hobby-grade epoxies (BTW the get new 3M purple "pro grade" sandpaper, it will sand anything without loading up, I've been throwing out all my old stuff) and is really tough.

CA is a lot faster if you're in a hurry. One good coat of thin type (I use Zap in the 1 and 2 oz bottles), sand, follow with diluted spot putty filler, sand again. Perfect paint-ready balsa NC in 30 minutes.

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Good tips Dave, thanks. The more alternate cat-skinning methods the better . I'll look out for the 3M sandpaper.

Have you ever tried spray lacquer? I wonder how that would turn out.

dbc said:

Have you ever tried spray lacquer? I wonder how that would turn out.

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No but I'd like to. Do you have a brand recommendation ? Rusto Painters Touch enamel spray cans has been my paint of choice for awhile now. The only lacquer I know of is the little (5 oz ?) cans of Testors. I should get some for my next small rocket, just not as economical as the enamel.