Pre Painting Fins and Body Tube

I prefer to pre-paint the fins before attaching to the BT. I mask the base of the fins before painting, then sand lightly after to get a flattened balsa surface with no paint on them.

Has anyone had any luck pre-painting the tube, then gluing the fins to the painted BT surface. It would make things a lot more simple and look a little better.

I have done things like this. Sure it works, is probably less hassle than masking, and can up looking as good as well-done masking.

Downside is that you have to mask off the part of the body tube the fin attaches to, for good adhesion. Then tacking on the prepainted fins to the prepainted body tube will leave a weird little edge of unpainted joint between the fin and tube. Easier to glue your unpainted fins to your unpainted body tube, mask appropriately, then prime and paint.

I painted fins before I learned about fillets, after learning that only way to get a good paint job is to paint after...imo

kyle said:

Downside is that you have to mask off the part of the body tube the fin attaches to, for good adhesion.

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Yes, if you paint and then glue, your fins aren't glued to the body tube, they're glued to the paint. The only thing holding your fins to the body is the paint. So it won't take much for the fins to fall off, taking some paint with them, and they will then need to be glued back. If you've learned your lesson then you'll glue them on before painting over the joints.

Dredger said:

I prefer to pre-paint the fins before attaching to the BT. I mask the base of the fins before painting, then sand lightly after to get a flattened balsa surface with no paint on them.

Has anyone had any luck pre-painting the tube, then gluing the fins to the painted BT surface. It would make things a lot more simple and look a little better.

Click to expand...

Some photos are in order. I'd like to see how pre-painting works out for the finished model.

I don't think I'll be doing any pre-painting myself, but I'd like to see how it works out for you. How do you deal with the reinforcing fillets? I'd be afraid of having fins pop-off like dead leaves in a high wind. I must be missing something here. It wouldn't be the first time.

Dredger said:

I prefer to pre-paint the fins before attaching to the BT. I mask the base of the fins before painting, then sand lightly after to get a flattened balsa surface with no paint on them.
Has anyone had any luck pre-painting the tube, then gluing the fins to the painted BT surface. It would make things a lot more simple and look a little better.

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I tried what you are talking about years ago. The bond isn't as strong.
I had many fins pop off on landing.
Now, I usually prime the fins and body tube separately before gluing it all together - but, most all the primer is sanded off and I remove more primer (down to the brown tube)
where the fin root edge is to be glued.

Adrian has it right:
"Yes, if you paint and then glue, your fins aren't glued to the body tube, they're glued to the paint. The only thing holding your fins to the body is the paint. So it won't take much for the fins to fall off, taking some paint with them, and they will then need to be glued back. If you've learned your lesson then you'll glue them on before painting over the joints."

Dredger said:

I prefer to pre-paint the fins before attaching to the BT. I mask the base of the fins before painting, then sand lightly after to get a flattened balsa surface with no paint on them.

Has anyone had any luck pre-painting the tube, then gluing the fins to the painted BT surface. It would make things a lot more simple and look a little better.

Click to expand...

IMO it's a complete hassle. Why would anyone paint this way???

All the pre paint I done the fins always fall offs. So now I Just go with the hassle of painting and covering with blue tape, making sure that you remove the tape before it sticks and breaks the paint.

another option would be not bother and paint the lower section (fin can) the same color. save a lot of hassle masking everything off.

Dredger said:

I prefer to pre-paint the fins before attaching to the BT. I mask the base of the fins before painting, then sand lightly after to get a flattened balsa surface with no paint on them.

Has anyone had any luck pre-painting the tube, then gluing the fins to the painted BT surface. It would make things a lot more simple and look a little better.

Click to expand...

Pre-painting, no; but pre-sealing and primering, yes. You mask the root edge, and scrape the primer off the tube where you are going to attach. Then after attaching the fins and making the fillets, you use a last coat of primer on the fillets.

Another way would be to build the rocket with through the wall construction. That way you can do all your filleting on the inside, leave the fin tabs unpainted for maximum adhesion, and it looks good if the 'slots' are tight with the pre construction paint option.

FC