Balsa NC Curse

[rosko_racer]

AAAAAAAAAAARRRRRRRRRRrrrrrrrrrrrrrggggggggggggg!!!!!!!!!!
Everytime I paint a balsa NC with spray paint I get those bubbles.

No matter what I do: sand and seal with wood filler, paint and repaint, sand again, keep it in a warm place. Nothing I do works. I am thinking that I may have to seal the balsa with some other sealer/filler. Any thoughts or recommendations.

- Raul

 

[RoyGreen]

Originally posted by rosko_racer
AAAAAAAAAAARRRRRRRRRRrrrrrrrrrrrrrggggggggggggg!!!!!!!!!!
Everytime I paint a balsa NC with spray paint I get those bubbles.

No matter what I do: sand and seal with wood filler, paint and repaint, sand again, keep it in a warm place. Nothing I do works. I am thinking that I may have to seal the balsa with some other sealer/filler. Any thoughts or recommendations.

- Raul

Can you post a picture of these bubbles so we know what exactly you're talking about?

 

[Buzzard]

Was it a humid day when you painted? I find that it does matter here in North Texas.

Chas

 

[Stymye]

what brand of paint/ primer/ect... ?

 

[rosko_racer]

Paint: Krylon Interior/Exterior, 1501 glossy white

I painted in the basement of my house. I should not be humid because of the heater, it sucks the humidity from everything here. The nose cone had a coat of Elmers Carpenters Wood Filler applied a couple of days ago. I sanded it yesterday and applied a coat of paint today... see the results...

 

[rosko_racer]

OOpsss.....forgot the picture... lets try this one more time.

 

[foose4string]

I'm assuming your using a primer after the wood filler? Perhaps the wood filler and/or primer is not completely dry and the nosecone is soaking up alot of moisture. I wouldn't attribute this to balsa specifically, just appears something hasn't dried completely undernerneath.

 

[rosko_racer]

The NC did not have a primer coat. I did apply a coat of paint yesterday and hanged the NC over one of my board heater vents so it took some heat all night. I resanded again to get rid of yesterday's bubbles. Today it did it again... no use. I did paint a small NC with one of those Testor Paint Markers and it did not bubble up. Microwave it?

 

[rocketkyle]

try primer, I've never had that problem

 

[DaveCombs]

Hey rosko:

First, DON'T microwave it. That will make your problem far worse. I'd just bring it inside and let it sit at room temperature; there's no need for putting it over a heater. If it' comfortable for you, it should be OK for the paint.

Second, are those really air bubbles, or are they paint drops? I've had that happen to me too; it seemed to do it when the temperature was colder.

And yes, you owe it to yourself to use primer, because not only can it help hide defects on the surface, but it's a much better material for the paint to adhere to.

 

[Rocketboy89]

It looks to me like paint splatters...ive had that happen to my rockets when i paint.

 

[Stymye]

I've had very simmular spots when there was moisture on the rocket. even tho it looked dry.

 

[rokitflite]

You're not painting in the shower again are you Raul? You are married now, some things have GOT to change!

 

[rosko_racer]

Originally posted by rokitflite
You're not painting in the shower again are you Raul? You are married now, some things have GOT to change!

You are killing me here, Scott! No, I stopped painting in the bathroom (things have changed!!!)

They are bubbles and not paint splatter. Once the NC was painted the paint looked really good, nice coat, flat, an even coat. But after about 40 seconds the bubbles started to come out and got pretty big. They shrunk as the paint dried until they looked like you see in the pictures.

From now on is primer after that wood filler. Thanks guys for your comments and suggestions... Ah, I mentioned the microwave as a joke. Looks like it was a good one!

 

[dcastle]

Are you using sanding sealer before you paint? I'm a big fan of aerogloss and there are others, of course, but if you paint balsa without sealing it first you are likely to get all kinds of results like this.

 

[DaveCombs]

Originally posted by rosko_racer
Ah, I mentioned the microwave as a joke. Looks like it was a good one!

I only say that because I played that joke on myself once. My son's raingutter regatta boat needed to dry quickly, and we had painted it with Testor's spray. He suggested we try it, and never having done it before, I said, "Sure, what's the worst that could happen?"

Bad idea. Trust me on this one.

 

[rosko_racer]

Originally posted by DaveCombs
I only say that because I played that joke on myself once. My son's raingutter regatta boat needed to dry quickly, and we had painted it with Testor's spray. He suggested we try it, and never having done it before, I said, "Sure, what's the worst that could happen?"

Bad idea. Trust me on this one.

Any pictures? would like to see if you have them.

I heard of Aerogloss so much that I may go to the "hobby shop" today after work and get me a bottle. Scott: Call the shop and tell them to set aside one for me marked "special discount"

I have Sandman's LTV Scout and may try the Aerogloss on it.

 

[foose4string]

Aerogloss is good stuff. I like the "sanding sealer" better than the "balsa filler", so I would recommend getting that if you can. Takes at *least* three to four coats to fill completely, but comes out smooth as a baby's butt after its been sanded. It's defintely worth a try, just remember to let it dry completely, it takes some time. Honestly, I don't bother much with aeroglass anymore. A coat of FNF and a couple coats of primer usually does the trick. It's still a good idea to use primer with aerogloss.

 

[Micromeister]

Raul:
I've seen this alot lately in some of the "newer" balsa cones i've recently gotten in kits.
I'm thinking it's outgasing moisture from the cones themselves. Just last evening I was using min-wax wood hardener on a Aerobee-Hi scale model that produced all kinds of these bubbles. Had a couple other recently purchased kit cones produce bubbles under Pactra aerogloss Balsa filler, and Clear dope thinned 50/50 as well as a primed cone from another while a BNC-50Y out of my "Old stock" showed no sign of air bubbles sprayed at the same time??
Could very well be moisture content from "Greener" new balsa???? Since the air around here has been so darn dry lately maybe that's what's causing the problem???
I kinda doubt its your paint or primer involved, I'd lean more toward environmental issues.
I think I'll try drying some of these recently purchased cones and fin stock then prime them seperately (Not in the microwave)
Something else to experiment on

 

[SRP Crew]

Here's a bit of a long shot, but works for me.

If you have wood filled and are ready for primer, run your primer and paint under 90 F hot water for minute. For me, this will at least eliminate any spray issues.

If your storing your spray cans where it's a little cooler, this may be an option for you.

Hopefully your wood isn't green too. That'll be a whole other issue.

Good luck

Rick

 

[Balltip]

I see this happen a lot in my work when gluing porous materials (roughened leather) with different types of acetone based contact glues. What happens is that the glue seeps into the material quite quickly as the material is absorbent. Then, as the glue starts to dry the surface dries the fastest. The vapours coming from the glue that has penetrated the material then gets stuck under the partly dried surface - causing it to "bubble".

So from what I can see, you had a few small pores that were not quite filled. The paint soaked into the balsa and caused the bubbles. Good thing is that now you NC is most likely sealed properly and it won't happen again!

 

[Stymye]

I'm gathering from most of the replys that the problem could be stemming from the fact that the balsa my not be as "dry "as normally found.

this makes sense to me , as my problem was moisture in the compressor rig that I dusted my rockets off with, after sanding.. it was leaving an invisable layer of moisture on the rocket.

when I saw your photo ,thats exactly what mine looked like a few minutes after painting.

 

[Micromeister]

Bingo Stymye!
That's exactly that same looking "bubbles" seen on the different paints and primers lately.
10 to 1 drying these balsa parts will eliminate the problem. seems more and more like green wood

 

[rosko_racer]

Today I received an order I made last Thursday from Semroc. There are a few NCs in the box. I was thinking about placing them on top of the heater registers on my 2nd floor for 24 hours to ensure they have the least humidity in them.

 

[rosko_racer]

I think (something I do not do much lately...) that one of my problems with what is mentioned in this thread is that I am using watered-down elmer's wood filler which it will be absorbed by the NC. The water will go deep into the wood. One solution to this may be that once the wood filler is dried and sanded to ones like, let it dry for one week to ensure that there is little or no humidity in the balsa.

... Then again I do not want to wait that long... I am thinking about using some kind of brush-on clear coat of enamel or acrylic to seal the wood and then use a filler... or maybe a few coats of the clear then sand it down... Just a thought...

 

[rosko_racer]

.... I did not know I had these in the garage... time to experiment...

 

[doug_man_sams]

Originally posted by rosko_racer
I think ... that one of my problems with what is mentioned in this thread is that I am using watered-down elmer's wood filler which it will be absorbed by the NC. The water will go deep into the wood.

No, that's not the problem. The problem is you cannot apply paint directly to FNF, thinned or straight. Nine times out of ten, you'll have problems. You gotta put some primer between the FNF and the finish coat. You don't need a different filler; you just need primer.

Doug

 

[redraindrop]

I agree with Doug.

Being a former autobody finisher/painter I know from lots of past experience that you must always follow bodywork with primer before final paint. Whether it's over bare metal or bodyfiller, there always has to be a substrate/sealer put down before a finish coat can be applied. This applies to all wood-based materials (balsa NC's) as well.

Also, the best results are attained by sanding between coats of primer. This fills any imperfections and allows for a smoother finish. With the FNF you used, you need to completely seal that off from the finish coat with the primer coat. That way it won't react with the finish coat or the finish coat won't try to invade any craters it finds. Also make sure your primer and finish are compatible with each other. Worse things lie ahead if they don't.

That may not guarantee a perfect finish - some of that depends on other conditions such as humidity, weather and, of course the type of paint used and how it is applied.

Good Luck!

 

[Micromeister]

What the last two posters seem to have missed is the bubbles we're talking about have shown themselves in first primered surfaces as well.
Drying these apparently green or mositure heavy balsa nosecones seems to be doing the trick.
I've just sprayed 6 new cones from two different manufactureres, 2 fliskits and 4 simroc kits after baking them in the oven at 325° for a couple hours. After cooling, they were sanded and sprayed with my normal cheapy grey primer.
Not bubbles. I believe we have the culprit, It's the mositure in the balsa that's bubbling the the paint and primer.
Hope this helps Raul