Can't avoid bubbles in bondo

**cyberlancer** · 06-10-2006, 07:49 AM

Hi, I'm trying to embed my monitor into my RR dash and the works since now seems quite good. Now, after a huge amount of time spent on sanding everything smooth I'm on the way to finish the job before painting the dash.
Problem: even after some multiple layer of bondo (thinner each time), I can't avoid that some very small bubbles remain trapped inside it, so, when I smooth the surface as a result I have small holes somewhere. How can I produce a completely smooth surface? Am I doing something wrong? Or is there any specific product (i.e a very liquid or microfine bondo?).

Thanx alot for any precious information.

**Sonicxtacy02** · 06-10-2006, 08:20 AM

You need to mix your hardener so that the bondo is thicker. Bubbles came for me only when the mixture wasnt right.

**Pepe** · 06-10-2006, 10:09 AM

You can just use a spot putty to fill the little holes. It comes in a tube like toothpaste and you just smooth it over the little holes and fill them.

**vfinterceptor** · 06-10-2006, 10:40 AM

Most times bubbles are induced while you are mixing the resin and hardner compounds. Think about it, when the resin is in the can there is no air bubles in it, the air is induced by the handling and mixing process.
If you are "stirring" them together rapidly, you will trap air in the filler.
To minimize this, mix your filler on a flat palate and use a spreader to fold the mixture until the hardener is throughly mixed. This will not eliminate all the air, but it will minimize it (if you do the technique properly there will be virtually no air) and require less spot putty to finish.

Cheers

BJ

**Shadow** · 06-13-2006, 12:28 PM

What I like to do is wait until I get the shape where I want it even if there are pinholes or whatnot and then I mix up my secret weapon; bondoresin. Take some body filler (bondo) and mix some fiberglass resin into it and mix it all up. If it's not the consistency of cold maple syrup when you stir it, add more resin. Then mix equal parts cream hardener and mekp(the resin hardener). Depending on what you're working on you can either brush it on or do what I like to do and pour it on top. Gravity will do the rest.

If you want to get all of the bubbles out of mixed bondo then you could put it in a vacuum to pull all of the air out.

High-build primer is your friend too.

**cyberlancer** · 06-13-2006, 12:37 PM

thank u all for precious information/hints.

cheers.

**sweetlikealemon** · 06-14-2006, 04:19 AM

Using high-build primer gets rid of pin holes after a layer or 2, it also produces a nice finish when sanded.

**DrMacZed** · 06-14-2006, 03:57 PM

What about using Bondo glazing putty? I thought that was supposed to go over top of bondo or what ever brand body filler you are using to fill pits, and air bubbles etc and, since it cures harder than bondo it leaves smoother, tougher finish similar I am sure to the above mentioned 'Bondo resin" concoction.

**Shadow** · 06-14-2006, 06:39 PM

Bondo resin has all the good properties of both without the drawbacks. Because it's thick from the body filler, it evens itself out and doesn't flow as fast as the resin.

Glazing putty is the same as what Pepe said it's also called spot putty. I usually use bondo resin after I've laid a couple layers of cloth down and knocked the high spots down. It evens out a lot easier than straight bondo and there's usually less sanding involved.