Glass bubbles?

[WizeOne]

Anyone use these? I mixed up a batch for filleting on a concrete form. It seemed like it took a lot more 'bubble' to get to peanut butter than it does for cabosil.

Anyway, I mixed it, applied it and subjected it to my 'heat oven' (cardboard box with space heater aimed at opening) 'cause it was too cold out and I wanted to continue working on the form/mold.

A day and a half later I went to sand it down and the although it appeared dry/cured, it just rolled off bits and pieces as I sanded it. I thought maybe my epoxy (3:1) was getting old but for the next batch I just used cabosil and I was sanding away nicely, six hours later.

Is this a normal characteristic? I thought it was the stuff to use for easy sanding.

 

[ondarvr]

Re: Glass bubbles?

Adding just one type of filler normally doesn't work as well as adding a combination of them, try adding both next time. Just adding bubbles to thicken it most likely reduced the volume of Epoxy to the point where it wouldnt cure correctly or there just wasn't enough epoxy to hold it together. Silica will keep it from sagging, bubbles will make it easier to sand and lighter.

 

[Mark42]

Re: Glass bubbles?

Adding just one type of filler normally doesn't work as well as adding a combination of them, try adding both next time. Just adding bubbles to thicken it most likely reduced the volume of Epoxy to the point where it wouldnt cure correctly or there just wasn't enough epoxy to hold it together. Silica will keep it from sagging, bubbles will make it easier to sand and lighter.

Yes, this has been my experience exactly. Glass bubbles by themselves do not make a good putty in epoxy.

Search for " EZ Thick" on yahoo. Its cheap and works well.

 

[WizeOne]

Re: Glass bubbles?

Thanks all. That's what I ended up doing for subsequent coats. I added cabosil until it neared the consistancy I wanted then finished it of with the glass bubbles. (probably 2/3rd by 1/3rd or so) It cured quickly and seems to sand fine, albiet like iron.

I'm making a mold for two entry walk concrete light pier top caps. I could not find the size, shape or color I needed so I decided to cast them myself. I originally tried to do the filleting with bondo but it was leftover stuff from working on my sons car about 4 years ago. It seemed to want to cure up rapidly after I mixed it but never dried once in the form. I had to scrape it all out and re-do it with the epoxy.

I'd hate to add up all the time I have in this. The caps better come out perfect.

I know this isn't boat resto, but I figgered this was the best place to get epoxy info.

 

[Bondo]

Re: Glass bubbles?

Ayuh,... Pretty elaborate concrete Form,....

As you figured out,...
Cabosil is a Thickening agent,+ the Bubbles are a Bulking agent....
2 different things for 2 different tasks....