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Filler for Glass Fuselage Seam Work

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Filler for Glass Fuselage Seam Work

Old 03-20-2022, 04:39 PM
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tgilkey
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Default Filler for Glass Fuselage Seam Work

I'm doing the seam on a glass fuselage and would like some recommendations for products to use that are better than "bondo," available, and don't sand like iron... The fuselage appears to have a very light coating of primer shot in the mold. The plan is to use Klass Kote epoxy paints for primer and colors. Products for seam fillers and advice for using will be appreciated. I have done several planes over the years but never often enough to feel like I know where I'm going...

Thanks, Tom
Old 03-20-2022, 05:53 PM
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RCFlyerDan
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Default My techniques.

Originally Posted by tgilkey
I'm doing the seam on a glass fuselage and would like some recommendations for products to use that are better than "bondo," available, and don't sand like iron... The fuselage appears to have a very light coating of primer shot in the mold. The plan is to use Klass Kote epoxy paints for primer and colors. Products for seam fillers and advice for using will be appreciated. I have done several planes over the years but never often enough to feel like I know where I'm going...

Thanks, Tom
Hey To,

I prefer to use 3M Acrylic White Glazing Putty. There isn't any mixing. It dries very quick, provided it is skimmed on the surface to be filled. Only do one pass over the areas of issue. It starts to dry almost immediately, so two passes makes a mess. It isn't for filling big cracks or holes. If you do, it shrinks, so you have to fill a couple times. I also prefer wet sanding with wet 220, the black sandpaper. Then for pre sealer or primer, I finish with wet 500. Sanding the sealer or primer with wet 500, you will be able to see the high and low spots. Apply glazing, if needed. A skim coat of glazing over newly applied fiberglass will help fill the weave. Usually dries enough in an hour to sand. Before paint, a sealer or primer is needed. I prefer a urethane sealer or 2K primer. If I am getting ready to paint a smooth sealed/primed fiberglass surface, I wet sand with wet 500 black sand paper.
I have used K&B and KlassKote epoxy paints. I switched over to urethane paint several jets ago. Urethane paint is much easier to spray. Mixed only with reducer, colored paints can be put back into original can with no issues. So the paint goes further if you accidentally take too much out of the can to spray. Dries within an hour for wet sanding, so you can fix issues, maybe even using the glazing putty to fill issues, sand, and continue spraying the same day. Only the sealers, primers, and clear coats can't be saved or put back in the can. This is because it is mixed with a hardener.
I quit using KlassKote a long time ago for several reasons. This is because it is an epoxy, it cures, rather then evaporating, thus adding considerable more weight. Takes a day to cure, before sanding, fixing issues, taping for the design and adding next colors. If you tape too soon, tape can leave a tape imprint in the paint surface. If you spray too heavy of a coat, there is a risk of sagging, and having to wait at least two days to cure to fix. Gums up the spray gun, and difficult to clean out of the gun, because it is curing and becoming a sticky mess.
Here is a picture of the glazing putty on Amazon.


It's worth the money, and last for more then a year in the drawer.


Stay Safe! Stay Well! Dan
Old 03-20-2022, 06:13 PM
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RCFlyerDan
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Here are a couple examples.


I filled the corners with the glazing.

Here you can actually see the cloth and how the glazing filled and sanded.

Here I used the glazing to fill the low spots and weave. I'm making a radio tray.

The radio tray finished with urethane paint and clear coat.

The finished radio compartment.


Old 03-21-2022, 07:06 AM
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speedracerntrixie
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For doctoring up a seam I just mix up some Klass Kote primer and add some micro balloons to make a thin paste. It can then be brushed onto the seam. The glazing putty can be used too but are heavier and shrink more.

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