What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Pinhole Filler

SeanB

Well Known Member
Looking for a quick fix to delete some remaining pinholes in wheel pants, fairings. Filler primer was applied already. Have these products on hand. Purple is acrylic based, Bondo is polyester. Recommendations? Thanks!
 

Attachments

  • 536C1366-2D24-4742-976A-77E723362992.jpg
    536C1366-2D24-4742-976A-77E723362992.jpg
    434.5 KB · Views: 84
Bondo

I use the Bondo. Dries super fast.
I prefer Dan's method to finish fiberglass. Very few imperfections to fix.
 
Looking for a quick fix to delete some remaining pinholes in wheel pants, fairings. Filler primer was applied already. Have these products on hand. Purple is acrylic based, Bondo is polyester. Recommendations? Thanks!

Sean, either is fine, with a caveat. Squeegee them into the pinhole with some force. When when cured, sand off all trace, leaving only the filler down in the pinhole.

You mentioned "filler primer applied already". What product did you use?

Please share ......I could use a less work method for fibreglass

Not "Dan's method". Sealing the surface with epoxy skim coats has been around for quite a while now. It's usually attributed to Cory Bird, as seen on his awesome scratch built airplane he called Symmetry (below). Very common among composite builders, with examples on the web.

I'm not going to call it "less work", as it involves block sanding the entire surface after the epoxy skim coats are cured. That said, when done correctly there will be little else to do prior to primer, primer surfacer (if desired), and paint. And it's bulletproof; epoxy on epoxy, no mix and match chemistry under your paint. Remember the Chinese menu..."Cheap, fast, good, pick any two."

Examples in posts 15 and 68, and an epoxy shelled mold form in post 69:

https://vansairforce.net/community/showthread.php?t=22931
.
 

Attachments

  • Symmetry.jpg
    Symmetry.jpg
    62.9 KB · Views: 92
Looking for a quick fix to delete some remaining pinholes in wheel pants, fairings. Filler primer was applied already. Have these products on hand. Purple is acrylic based, Bondo is polyester. Recommendations? Thanks!

NEVER, EVER use the red, one part Bondo glazing stuff. It will create serious problems after paint. It is from the lacquer paint days and only works with lacquer paint systems. ONLY use two part fillers. Bondo makes both the red stuff and the polyester with activator (which is ok to use) in that tube size, so use caution.
 
Last edited:
NEVER, EVER use the red, one part Bondo glazing stuff. It will create serious problems after paint. It is from the lacquer paint days and only works with lacquer paint systems.

See the previous caveat. Not a problem if all of it is sanded away, leaving only the tiny bit down in the pinhole.

Used as a glaze, i.e for surface build? Yes, bad idea.
 
Thanks all for your replies. For a friend's plane and he used rattle can Duplicolor Filler Primer for now. He has a paint date later this year.
 
Thanks all for your replies. For a friend's plane and he used rattle can Duplicolor Filler Primer for now. He has a paint date later this year.

Tell him the rattle can primer is a pointless waste of time and money. If the painter is any good, he will sand it off and start over with a two-part primer.
 
See the previous caveat. Not a problem if all of it is sanded away, leaving only the tiny bit down in the pinhole.

Used as a glaze, i.e for surface build? Yes, bad idea.

I use a glaze called Nitro-Stan. It’s a lacquer based red putty. The smaller the spot the better. If you need to fill something, use body filler or a 2 part glaze like Evercoat 417. The red putty is for when you just have a few pinholes left. If you have too big a spot of red putty, it never completely dries. It just skins over. After you paint over it, you get a blister right there.
 
Finishing

Please share ......I could use a less work method for fibreglass

Whoever came up with it, it works. :D
However, it's work no matter how it's done.
I find the method leaves far fewer imperfections.
Lots of detail on my blog. Feel free.
http://wirejockrv7a.blogspot.com

Here's a short version with some changes from how others do it. This assumes a finished fiberglass part.

-Mix micro. I dilute 10% by weight with Denatured Alcohol. I tried all the solvents and it worked best. It allows more micro in the mix and a thinner consistency. More micro means it sands easier after curing. The caveot is the alcohol evaporates quickly so you have to work really fast. Squeegee a layer all over the part and cure. Easier to work small batches. If it gets chunky, stop and mix another batch.
-Block sand with 40-80 till the rough areas are gone and it's getting close to flat. Switch to finer grit to make it smooth. Use whatever forms available to get the surface flat. PVC pipe, birch plywood, rubber block, etc. Never use a bare hand. It causes surface irregularities.
-Mix neat epoxy and squeegee it on forcing into the surface. Let it cure 30 then repeat. Some prefer to roll the surface with a dry roller for texture. The idea is it helps see the surface go flat when wet sanding next step. Your call. I prefer to brush it on with a chip brush.
-Block sand. Wet is easier. No bare hand. Don't break through the epoxy.
-Apply a primer. I prefer two brushed coats 1 hour apart. Cure
-Wet sand to 220.
-Fill any imperfections with a glazing putty. Cure
-Wet sand to remove glazing leaving imperfections filled.
-Prime and paint.
-Cut& Buff
 
Back
Top