Bought some sanding sealer - now I have questions

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lcorinth

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I just got one ounce of Aerogloss sanding sealer. I've been frustrated with CWF for fin filling lately (warping, pock marks), and wanted to try something new.

Now, I realize I didn't consider a few things.

First of all, I didn't order a brush. I guess I thought there would be one attached to the underside of the cap, like with rubber cement. Oops. Oh, well. I can get a brush.

But I didn't get any thinner, or anything to clean it with.

This stuff looks pretty thick. Am I supposed to brush it on as-is, or am I supposed to thin it before use? If I'm supposed to thin it, what's the ratio? And, can I thin the whole thing, keep it in a container, and use it when I need it, or do I need to thin just what I'm going to need for one project?

Then: Cleaning. I guess I use the thinner for cleaning, but what do I do? Just soak the brush in the thinner and then squeeze everything out with a paper towel? Soak the brush then run it under water?

Also, I've seen other sanding sealers which are not packaged for "rocketry." Will any of these work to get a smooth finish on fins, or do I need to look for something specific? And with non-rocketry sanding sealers, again, do I thin them?

Thanks!
 
Use the sanding sealer full strength. I like a quality brush, fairly large, so I can paint it on with minimal brushing. Clean up with lacquer thinner. I do woodworking, and buy it by the gallon, but you can buy quarts, too. Lowes or Home Depot has it in the paint department, or check with your local hardware store.

I use small pill bottles or mason jars to keep small amount of thinner for cleaning a brush. When it gets really dirty, just pour onto an old rag and let it evaporate. Do this outside, so fumes don't make your house smell!
 
Clean up is best with lacquer thinner, but believe it or not, you can get by without cleaning your brush, if you want. The sanding sealer itself has some pretty good solvent properties, so if you insert a hardened brush into it, it will be pliable in a few minutes.
 
OK, and just so I know I'm not crazy, sanding sealer on fins usually goes on after the fins are on the rocket, right? I do my CWF stuff beforehand, and it always slows me down.
 
Use the sanding sealer full strength. I like a quality brush, fairly large, so I can paint it on with minimal brushing. Clean up with lacquer thinner. I do woodworking, and buy it by the gallon, but you can buy quarts, too. Lowes or Home Depot has it in the paint department, or check with your local hardware store.

I use small pill bottles or mason jars to keep small amount of thinner for cleaning a brush. When it gets really dirty, just pour onto an old rag and let it evaporate. Do this outside, so fumes don't make your house smell!

Can I use any carpentry product I find at Home Depot labeled "sanding sealer" on balsa fins? Do you have a brand you prefer?
 
One thing you could do is combine papering with sealing, you'd get a really strong fin after that.
 
OK, and just so I know I'm not crazy, sanding sealer on fins usually goes on after the fins are on the rocket, right? I do my CWF stuff beforehand, and it always slows me down.

Typically, yes. But I really like to seal fins when possible while still in the balsa sheet. Easy to do, and really easy to sand. Pop them out, sand airfoils if desired, and then seal those edges.

Can I use any carpentry product I find at Home Depot labeled "sanding sealer" on balsa fins? Do you have a brand you prefer?

I've used Deft Lacquer Sanding Sealer in my shop, and tried it last year on balsa fins and nose cones. It works well, but does take more coats than the modeling sanding sealers like Aerogloss. A quart is only around $11-12! That makes it dirt cheap compared to those little 1 oz. bottles, still super cheap compared to the larger bottles of Aerogloss and similar. For me, I start filling fins and nose cones immediately when I open it kit, so if I need 6-8 coats of Deft, vs. 3-5 coats of Aerogloss, it doesn't make too much difference.

With the Deft, it does seem to settle more, so make sure you stir it very well. Some of the settling is probably because my Deft can is a few years old, and so it settles like you'd expect with varnishes, paints, etc. I fill up old empty Aeroglass jars so the stirring of a few ounces is much easier than opening up the quart can every time I need to seal some balsa.
 
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Typically, yes. But I really like to seal fins when possible while still in the balsa sheet. Easy to do, and really easy to sand. Pop them out, sand airfoils if desired, and then seal those edges.

Interesting. Sounds like a good idea. I hadn't thought of sealing it first, then sanding the airfoils and sealing just the edges. So, if you get sanding sealer on the root edge, that doesn't make the glue less effective?

There's a hardware store near where I work, and they have Minwax sanding sealer. They have it as a liquid for brushing on, and in a rattle can. That sounded interesting to me, except I guess I'd have to mask off the rest of the rocket first.

But it might be good if I applied it to plywood fins before attaching them to the rocket - just mask the tabs and spray on the Minwax, sand, and repeat.
 
Interesting. Sounds like a good idea. I hadn't thought of sealing it first, then sanding the airfoils and sealing just the edges. So, if you get sanding sealer on the root edge, that doesn't make the glue less effective?

There's a hardware store near where I work, and they have Minwax sanding sealer. They have it as a liquid for brushing on, and in a rattle can. That sounded interesting to me, except I guess I'd have to mask off the rest of the rocket first.

But it might be good if I applied it to plywood fins before attaching them to the rocket - just mask the tabs and spray on the Minwax, sand, and repeat.

Brush sanding sealer with light applications near the root edge while fins are in the sheet. You don't want to seal the root edges. Be careful with the Minwax. I am not sure which product you are looking at, but it may not be lacquer-based. Lacquer dries fast, and so you don't have to wait long between sanding and additional coats. If the Minwax product you are looking at is a "wood hardener", proceed with caution. I've heard of "less than desirable" results with it. I do not recall where I read that, so maybe someone who has used Minwax products will chime in.

FYI, I bought my Deft sanding sealer at Home Depot.
 
Brush sanding sealer with light applications near the root edge while fins are in the sheet. You don't want to seal the root edges. Be careful with the Minwax. I am not sure which product you are looking at, but it may not be lacquer-based. Lacquer dries fast, and so you don't have to wait long between sanding and additional coats. If the Minwax product you are looking at is a "wood hardener", proceed with caution. I've heard of "less than desirable" results with it. I do not recall where I read that, so maybe someone who has used Minwax products will chime in.

FYI, I bought my Deft sanding sealer at Home Depot.

They were both lacquer sanding sealers. I only noticed them, because I was there looking for lacquer thinner after reading replies to this thread.

I think for now, to be safe, I'll just try applying the sanding sealer after the fins are glued on, so as not to seal the root edges. But perhaps I'll try it on a TTW fin, masking the tab off first, and then once it's filled, attach it to the rocket.

Thanks for your advice!
 
Dan, in addition to the root edge, you'd want to keep the balsa untouched where you put the fillets so that glue can adhere to the bare balsa.
Using the Aerogloss after the fillets have dried probably gives you the best results overall.
If you're at Tuesday's meeting, you can get some input from the others and John will be glad to talk papering with you.
 
I've used Deft Lacquer Sanding Sealer in my shop, and tried it last year on balsa fins and nose cones. It works well, but does take more coats than the modeling sanding sealers like Aerogloss.
I've used the Deft Sanding Sealer too, and I am pleased with it. The spray can version is a nitrocellulose lacquer.
 
I love the deft lacquer in the spray can. Makes it very easy to seal and sand fins and balsa cones after assembly.

kj
 
As a precaution, I've been wearing nitrile gloves when working with lacquer thinner, and also epoxies, because they can be absorbed. The latest Harbor Freight catalog has 100-pack of nitrile gloves on sale for $5.99. I think they typically are $7.99. I also bought the heavy duty, which are really tough. They are same list price I think, but in a box of 50. With the light blue regular gloves I get a few uses before I toss, usually from a tear. The dark blue heavy duty gloves seem to last forever.
 
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As a precaution, I've been wearing nitrile gloves when working with lacquer thinner, and also epoxies, because they can be absorbed. The latest Harbor Freight catalog has 100-pack of nitrile gloves on sale for $5.99. I think they typically are $7.99. I also bought the heavy duty, which are really tough. They are same list price I think, but in a box of 50. With the light blue regular gloves I get a few uses before I toss, usually from a tear. The dark blue heavy duty gloves seem to last forever.

That's a much better price than the ones I get from CVS!
 
Dan, in addition to the root edge, you'd want to keep the balsa untouched where you put the fillets so that glue can adhere to the bare balsa.
Using the Aerogloss after the fillets have dried probably gives you the best results overall.
If you're at Tuesday's meeting, you can get some input from the others and John will be glad to talk papering with you.

I did the fillets first, so that wasn't a problem.

Sorry I couldn't make it out to the meeting tonight. We had to do an EPIC grocery shop at Wegman's. But I'd love to talk papering with John. I've tried it a few times, and I just can't get the hang of it (although I've had some moderate success with Avery labels). Maybe if he can make it to the rocket build on Sunday, I'd love to chat with him about it.

Right now the issue is that I can't tell when I'm done with the sanding sealer. I brush it on, let it dry, and sand (400 grit)... Then I see scratch marks, and I swear I can still feel grain when I run the back of my fingernail over the fin.

Now, the fins I'm practicing on are balsa stock from either Michael's or Menard's, which is very soft stock with a loose grain, so I suppose I'd need more coats to fill that. But I've also been trying it on some scrap from a kit - hard balsa, very tight grain... And I see scratches and still think I feel some wood grain.

I've done maybe six coats or more on the balsa stock fins, and probably four on the kit balsa scrap. When do I stop and paint? Am I getting the sandpaper loaded up and scratching the surface? Am I oversanding? I'm trying to be gentle with it, but this is a new material for me.
 
Sealer, primer, paint. Your sealer is there to close up the grain on the balsa for the next step. I would say that after 6 coats you are ready for primer. Then sand the primer and repeat as needed.

kj
 
But I'd love to talk papering with John. I've tried it a few times, and I just can't get the hang of it (although I've had some moderate success with Avery labels). Maybe if he can make it to the rocket build on Sunday, I'd love to chat with him about it.

Unfortunately, I can't make it on Sunday, but next time we both make it to a meeting I'd be happy to show you what I do. It's nothing special, but I've had pretty good results. (Maybe I've only had "moderate success" as well, but my standards are lower. :) )
 
Sealer, primer, paint. Your sealer is there to close up the grain on the balsa for the next step. I would say that after 6 coats you are ready for primer. Then sand the primer and repeat as needed.

kj

So, it's okay if it's not perfectly smooth after the sealer?
 
Right. The primer will be your filler for any small imperfections. The sealer makes it so you can use less primer, as it keeps the primer from soaking into the open grain of the balsa.

kj
 
Right. The primer will be your filler for any small imperfections. The sealer makes it so you can use less primer, as it keeps the primer from soaking into the open grain of the balsa.

kj

OK, great. I think the rocket is ready, then.

I sure hope this works out well. I've been using CWF up till now, and probably will continue on some builds, but I have had some real issues with it. Particularly, if I'm doing a tapered fin, even if I press the fins after filling, there's a little wiggle room for the tapered part to curl up.

This sanding sealer also seems to dry a lot quicker than CWF pressed under a book. And I like being able to attach the fins first - that's the part of the build where I feel I've made a lot of progress. If I have to do several coats of CWF (which for me, can take days or even weeks, depending on my personal schedule), I feel like I can work on something for ages without seeing much for it.

Thanks for the advice.

Now, I need to find somewhere to prime and paint...
 
Unfortunately, I can't make it on Sunday, but next time we both make it to a meeting I'd be happy to show you what I do. It's nothing special, but I've had pretty good results. (Maybe I've only had "moderate success" as well, but my standards are lower. :) )

It's too bad you can't make it, John. Maybe the next one. I'd love to have you join us.
 
It's too bad you can't make it, John. Maybe the next one. I'd love to have you join us.

I wish I could be there, but I'm in a curling league on Sunday evenings, so most Sundays are no good for me until the season ends in April.
 
Dan, in addition to the root edge, you'd want to keep the balsa untouched where you put the fillets so that glue can adhere to the bare balsa...
My solution for that problem is to cut a strip of masking tape just wide enough to cover the root edge and about 1/8" to 1/16" (depending on the size of the rocket) of the fillet area before applying SS. I use a disposable 1/2" shop brush (also known as an "acid brush" - also insanely cheap at Harbor Freight) to apply the SS. I typically apply one thick coat, sometimes two, and since the SS dries so quickly I can peel off the masking tape, sand the fins to taste and glue them on within minutes.
 
I do the airfoils (usually just rounded leading and trailing edges), glue the fins to the rocket, fillet, then seal.
 
I wish I could be there, but I'm in a curling league on Sunday evenings, so most Sundays are no good for me until the season ends in April.

I understand - one must follow one's passions.

Hopefully, if people like the idea, it will be a monthly event. Then perhaps we'll see you there in the spring.
 
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