Finishing Balsa Cones

[Dseter]

I Know it's probably been covered before, but would like to hear how folks are finishing balsa cones to a nice shine(without making it a retirement project). I was thinking thinly sealing with wood glue, then sanding, then primer, sanding, then paint. Thank you!

 

[troj]

I Know it's probably been covered before, but would like to hear how folks are finishing balsa cones to a nice shine(without making it a retirement project). I was thinking thinly sealing with wood glue, then sanding, then primer, sanding, then paint. Thank you!

Wood glue doesn't sand well -- it's like trying to sand rubber.

You're better off with a balsa filler coat, which is meant to be sanded. Or, you could likely use a thin epoxy, or thin epoxy a bit with acetone.

The filler coat will be easier to sand.

-Kevin

 

[Dseter]

Ok, yeah, I have the preferred Elmer's wood filler I think. I've read about thinning it to pancake batter consistency, might try that method, thanks!

 

[ScrapDaddy]

Make sure you thin it out so you can paint it on

 

[Dseter]

Yeah, I've used filler in the past for big rocket projects(filling tube spirals, etc.) and really like it. It's nice that Estes brought back the bigger balsa cones like on the Photon Disruptor. I'll be sharing that one with my Blue Bird Zero but also have a balsa cone for a couple scratch Starlabs and a Clone Goblin. Will try to post the results!

 

[dragon_rider10]

What I do that works well is apply 3 or 4 coats of filler, allowing it to dry about 10 minutes in between, and then sand it down.

 

[Dseter]

OK, cool. I'll give that a try. Luckily, I need a few balsa cones to be a nice, shiny white so I should get a lot of practice.

 

[MarkII]

I have recently become really impressed with the performance of balsa nose cones that I have coated with laminating epoxy (aka "Finish Cure"). This variety isn't formulated for bonding joints, but rather, as the name indicates, it is for laminating materials together. It is very thin in consistency and can be applied with a synthetic bristle paintbrush. I apply one layer, let it cure and then sand it smooth. I usually then apply a second layer and repeat the process. Two applications is enough to do the job. The great thing about this stuff is that it sands really easily, yet it produces a satin-smooth surface when it is sanded. It also produces a hard, durable surface. It doesn't just sit on the surface of the wood, but really penetrates into it. I use it now on all of my balsa nose cones. (IOW, all of my nose cones.)

You need to give the epoxy several hours to cure, and when you are painting it on, you need to keep it off of the shoulder. I am a big fan of Duck Brand Perfect Release masking tape (the purple one). I used to get it at Walmart, but lately I have had trouble finding it there. Try getting it at a home improvement store. Also, wear nitrile gloves when you are working with epoxy. I give the nose cone shoulder a couple of wraps of the purple masking tape and also screw in a suitably-sized screw eye into the bottom before I paint on the epoxy. You can hold the nose cone by the taped shoulder when you are applying the coating, but as soon as you are done and the epoxy has stabilized and leveled out, you need to remove the tape. Don't leave the masking tape on very long; get it off as soon as it is practical to do so. That's when having the screw eye comes in handy; it gives you something to hold onto. The Perfect Release tape has a very soft tack, so it comes off easily without taking some of the balsa from the shoulder with it. Then I usually hold the nose cone horizontal while I twirl it back and forth to even up the coating until it starts to set up. You don't really need to do that, because you can easily sand down any drips or runs that form, but I like to do it. Then I hang the nose cone up by the screw eye on a long peg overnight so that the epoxy can cure.

MarkII

 

[luke strawwalker]

I Know it's probably been covered before, but would like to hear how folks are finishing balsa cones to a nice shine(without making it a retirement project). I was thinking thinly sealing with wood glue, then sanding, then primer, sanding, then paint. Thank you!

I harden my nosecones with CA, sand off the CA "grit" (hardened material and balsa dust raised by the CA) with 220 grit sandpaper, fill with thinned Elmer's Wood Filler (thinned with water to about the consistency of mustard) and then sand with 220 again, prime twice, sand with 220 grit, inspect in the light, reprime any spots that need it (if necessary) resand with 220 grit, damp sand with 600 grit, let it dry, and paint.

Sounds like a lot of work, but a nosecone is so small (even the large ones don't take that long) it really doesn't take a long time, and the effort is definitely worth it!

Mine turn out as smooth as plastic cones when I'm done... OL JR

 

[Micromeister]

Used to harden balsa nose cones with Minwax wood hardener or Delta Creamcoat a water based filler. but have found over time they really didn't add much other then another step to the sanding process.

I've since stopped most filler applications on wood parts going directly from base sanded raw wood to Cheapy Rattle can auto primers. Usually in a 3 coat/sand 3 coat sand process that completely fills all grain by the second 3coat application regardless of primer used. unless the cone or fins have really deep grain 220grit is generally as coarse as I need go stepping down to 320, 360 and occasionally 400grit to finish before applying the first base color coat.

Does it create some sanding dust? sure but that's what I have a vacuum cleaner for. do these cones get dents or dings? Rarely. It takes a lot more then just a hard landing to cause damage.

 

[MarkII]

I was going to mention Min-Wax Wood Hardener, but my post was already too long, so I dropped it. My experience with it has been positive, but be forewarned: it takes a LONG time to fully cure and harden the balsa. I'm talking weeks here. Seriously. I have used it on some large balsa nose cones, and at first I wasn't at all impressed. It was only after I had left the cones hanging on their pegs for a couple of months that I found out how effective it is, and that was by accident. While reaching for something else, I accidentally knocked a large elliptical nose cone off its peg; as it fell (from a height of about 4 feet) it bounced off a couple of hard objects and then hit the hard tile floor in my rocket room tip first. If it had been an untreated nose cone, it would have suffered severe trauma. That's what I was expecting to see when I picked it up, but I was astonished to find that it didn't have a mark on it. A few months later, I had a similar accident with another large nose cone that I had treated with the Min-Wax product. Same result, only in that case the nose cone had fallen straight to the floor.

But the product is getting to be hard to find. It's been over a year since I last saw any on the store shelves. Also, it's incredibly volatile and incredibly, ummm, aromatic. (I always apply it outdoors.) And then there's that very long cure time. I am absolutely not kidding when I say that you have to give the object at least two or three weeks, if not longer, to fully harden. Balsa draws the stuff in very easily, so it soaks in deep. That's a big reason why it is so effective, and also why it takes so long to cure. After a day or so, the surface will look and feel dry, but that's deceptive. The interior of the piece will still be soft. If you try to use it before the interior fully hardens, the cone will get dinged and gouged up just as easily, if not more easily, than a similar piece that was not treated. Hardening the interior is a slow process. You must be patient with it and let it do its job.

Another thing about Min-Wax Wood Hardener is that it does absolutely nothing for the surface finish of the cone. It doesn't fill the grain, although it may seal it (eventually). You will still need to use other products to prepare the surface. That's why I like using laminating epoxy; not only does it harden the outside of the nose cone, it also fills and seals the grain and it creates a very smooth finish when it is sanded. So Min-Wax Wood Hardener is an excellent product, and nothing that I have ever used or heard about does a better job of actually making a balsa nose cone very hard and resistant to damage, and not just on the surface, but also deep into the interior. I have reserved it for use on my largest balsa nose cones, which are the ones that I am most worried about damaging. The two biggest problems that I have with it are: it's a PITA to use, and I can't find it anymore.

Mark K.

 

[Dseter]

OK, cool ,thanks guys. I think I have enough data to surge forward and yet avoid a retirement project. I'm gonna try to just use the Elmer's wood filler with thin coats, then sanding, then primer, sanding, etc.
I've used epoxy and CA for many years but don't want to get that started again if I can avoid it on low power stuff.
Thanks for the info on the Minwax, I'll be sure to avoid that unless I start on a balsa cone in October, that way it can sit until Spring. Will post results in the near future, as soon as the weather shapes up for painting.

 

[foose4string]

I've never had Minwax Hardener take that long to dry. Never more than 24-48 hours. I'm a little surprised at how vastly different our cure times have been, Mark. I can only assume it is climate related. Not sure what else it would be.

 

[MarkII]

I've never had Minwax Hardener take that long to dry. Never more than 24-48 hours. I'm a little surprised at how vastly different our cure times have been, Mark. I can only assume it is climate related. Not sure what else it would be.

It may be related to the size of the nose cone. I have used the hardener only on larger nose cones - 2" and 2.34" diameter and 5" to 9" long. They were dry to the touch within a couple of days, but they were hardly dent-proof. A month later it was a different story. Because of the sizes of the cones, I brushed the hardener on with chip brushes, instead of dipping them. I kept applying hardener until the balsa wouldn't take anymore. That may sound like a lot, but it was actually just 3 or 4 brush strokes in each area. A week or so after the application, I lightly sanded the cones and gave them another application, because I was disappointed with how soft they still were. I hung them up and then moved on to other projects. I didn't touch the first pair again until a few months later when I had the little workshop mishap that I mentioned earlier. I figured out after hardening a third nose cone that the stuff was somewhere around 85-90% cured after a month or so. (That last 10-15% of curing probably requires a couple more months.) But that might have been specific to the nose cone sizes that I applied it to.

What sizes of nose cones have you hardened with it? The smallest one that I hardened with it was 2" in diameter by 5.3" long. Perhaps the cure time is significantly shorter when it is used on smaller pattern nose cones. But there's one other thing; I talked about the wood hardener and its slow cure time in another thread on TRF a few months ago. Someone (I forget who) responded that on knife-making forums that he also visits, knife craftsmen have mentioned using Minwax Wood Hardener to harden the wood pieces that are used in the handles. He said that they have also commented on the long cure time that it required, too.

The Adirondack region's climate is cooler than that of the mid-Atlantic coast, with lower average summer temps and a shorter summer season. But it still gets hot here for a few weeks in the middle of the year (and sporadically before and after). Perhaps I should amend that to say that it gets hot enough (70s and 80s during the day, 50s and 60s at night; on a handful of days each summer, it hits 90 or better). I doubt that the difference in average ambient temps between our respective locations could have produced such radically different cure times. Perhaps a day or two, but not a month or two.

Let me just reiterate that, in my experience, Minwax Wood Hardener is VERY EFFECTIVE in toughening up balsa nose cones when it has been given sufficient time to cure. I have never tried anything that worked better.

Mark K.

 

[MarkII]

Apologies to the OP; we (I) went off on a tangent and started talking about hardening the balsa, which was not what you asked about. My original post about laminating epoxy was my contribution to the discussion about putting a smooth finish on a balsa nose cone. Sorry for the excess lines of screen space that I subsequently took up.

Mark K.

 

[GregGleason]

I have recently become really impressed with the performance of balsa nose cones that I have coated with laminating epoxy ...

MarkII

Thanks MarkII for the tip. I plan to try that out. I know it won't make them bulletproof but it should toughen them up some.

Greg

 

[MarkII]

Thanks MarkII for the tip. I plan to try that out. I know it won't make them bulletproof but it should toughen them up some.

Greg

It goes a pretty long way, though, especially if you coat them, sand that layer smooth and then repeat the process one more time. I couldn't get over how silky smooth mine got with just a small to moderate amount of normal sanding (nothing exotic). I use BSI Finish Cure epoxy. You can use the brush for more than one application if you drop it into a jar that is filled with a couple inches of acetone as soon as you are done with the brushing. Swirl it around a few times and let it soak until all of the epoxy comes off. Wiping the bristles with a paper towel after soaking them will also help to remove the epoxy.

Mark K.

 

[luke strawwalker]

It goes a pretty long way, though, especially if you coat them, sand that layer smooth and then repeat the process one more time. I couldn't get over how silky smooth mine got with just a small to moderate amount of normal sanding (nothing exotic). I use BSI Finish Cure epoxy. You can use the brush for more than one application if you drop it into a jar that is filled with a couple inches of acetone as soon as you are done with the brushing. Swirl it around a few times and let it soak until all of the epoxy comes off. Wiping the bristles with a paper towel after soaking them will also help to remove the epoxy.

Mark K.

Where you getting this finishing epoxy?? You have to mix it like every other kind of epoxy correct??

Interesting...

Later! OL JR

 

[MarkII]

Where you getting this finishing epoxy?? You have to mix it like every other kind of epoxy correct??

Interesting...

Later! OL JR

Hobby shop. My bottles are re-branded with the shop's name (HobbyTown USA), but it is this stuff. Like every other epoxy, it comes in two parts (resin and hardener), that you mix together 1:1 just as you do with nearly every other type.

Aeropoxy also makes a laminating epoxy, and West Systems probably does too.

Mark K.

 

[troj]

Aeropoxy also makes a laminating epoxy, and West Systems probably does too.

AeroPoxy makes laminating and construction epoxies; what most people use is laminating epoxy. That's all West and Fibreglast make.

I've got a basswood nosecone on the desk next to me that I brushed a couple coats of Fibreglast epoxy onto, primarily to fill the grain and help protect it from dings. Required very little sanding to get it nice and smooth.

-Kevin

 

[The EGE]

I personally do use wood glue, precisely because I never have to sand it. I just spread it out with my fingers and it dries perfectly flat. It also adds a lot of strength to balsa. I've also used it to coat 1/8" plywood fins heading to the transonic regime; it adds strength and makes them perfectly smooth, every time.

If you need to be able to sand, though, you can't beat good old Elmer's wood filler.

 

[ScrapDaddy]

I was going to mention Min-Wax Wood Hardener, but my post was already too long, so I dropped it. My experience with it has been positive, but be forewarned: it takes a LONG time to fully cure and harden the balsa. I'm talking weeks here. Seriously. I have used it on some large balsa nose cones, and at first I wasn't at all impressed. It was only after I had left the cones hanging on their pegs for a couple of months that I found out how effective it is, and that was by accident. While reaching for something else, I accidentally knocked a large elliptical nose cone off its peg; as it fell (from a height of about 4 feet) it bounced off a couple of hard objects and then hit the hard tile floor in my rocket room tip first. If it had been an untreated nose cone, it would have suffered severe trauma. That's what I was expecting to see when I picked it up, but I was astonished to find that it didn't have a mark on it. A few months later, I had a similar accident with another large nose cone that I had treated with the Min-Wax product. Same result, only in that case the nose cone had fallen straight to the floor.

But the product is getting to be hard to find. It's been over a year since I last saw any on the store shelves. Also, it's incredibly volatile and incredibly, ummm, aromatic. (I always apply it outdoors.) And then there's that very long cure time. I am absolutely not kidding when I say that you have to give the object at least two or three weeks, if not longer, to fully harden. Balsa draws the stuff in very easily, so it soaks in deep. That's a big reason why it is so effective, and also why it takes so long to cure. After a day or so, the surface will look and feel dry, but that's deceptive. The interior of the piece will still be soft. If you try to use it before the interior fully hardens, the cone will get dinged and gouged up just as easily, if not more easily, than a similar piece that was not treated. Hardening the interior is a slow process. You must be patient with it and let it do its job.

Another thing about Min-Wax Wood Hardener is that it does absolutely nothing for the surface finish of the cone. It doesn't fill the grain, although it may seal it (eventually). You will still need to use other products to prepare the surface. That's why I like using laminating epoxy; not only does it harden the outside of the nose cone, it also fills and seals the grain and it creates a very smooth finish when it is sanded. So Min-Wax Wood Hardener is an excellent product, and nothing that I have ever used or heard about does a better job of actually making a balsa nose cone very hard and resistant to damage, and not just on the surface, but also deep into the interior. I have reserved it for use on my largest balsa nose cones, which are the ones that I am most worried about damaging. The two biggest problems that I have with it are: it's a PITA to use, and I can't find it anymore.

Mark K.

Is there a similar drying period for Basswood and spruce Nose cones?

 

[troj]

I've since stopped most filler applications on wood parts going directly from base sanded raw wood to Cheapy Rattle can auto primers. Usually in a 3 coat/sand 3 coat sand process that completely fills all grain by the second 3coat application regardless of primer used. unless the cone or fins have really deep grain 220grit is generally as coarse as I need go stepping down to 320, 360 and occasionally 400grit to finish before applying the first base color coat.

I'm trying this approach on Dan's Semroc Scout, though I'm using a decent quality (for spray paint) primer I happened to already have.

News at 11:00 for how it works out. First coat is drying, now.

-Kevin