Another Chipping Question

[Raymond Chapman]

We just chipped two glass pieces and had an unusually large amount of etched spots that did not chip. The glass was etched with silicon carbide - our first using this material. The glass was blown off with air before applying the glue.

Is this the result of not cleaning the class properly and possibly having etched the glass too deeply...or not enough?

Can we reapply glue over the unchipped areas and not ruin the overall look?

These were sample pieces, so no money is going down the drain.

[Larry White]

Hi Raymond-
I had that happen on my last one too. I had several places where the glue just didn't chip off. So I soaked it off, then painted an asphaltum border around it and flowed new glue over the selected areas. They chipped off fine and after cleaning you can't tell there was a patch job.

In my case, the glue didn't chip, I believe it was just a bit too weak. If it chips (peels) off leaving too much sandblast areas, it sounds like it didn't grab well enough. Perhaps the glue wasn't hot enough(?)

-LW

[Raymond Chapman]

Thanks Larry. In our situation, the glass chipped but left some rather large areas still just etched. It wasn't a case of the glue staying on the glass, although we have had that experience also.

Should we be be cleaning the glass with anything after blasting?

I'll use your suggestion and go back with asphaltum around the unchipped areas. Stay tuned.

[Doug Bernhardt]

Ray...Think it's a great idea using the silcon carbide abrasive and am willing to bet any probs are just related to the size of glass and distribution of the glue. It always seems arround here that the larger the piece the more we need to hustle through the steps...it sets(glue) at the same rate weather the piece is 12x12" or 5x5ft and spreading glue over larger areas tends to leave more sparcely done areas. Admittedly I still use the " cut the mask" method....always hated having a thinners bath sitting open in the shop when the jobs were still only several a year. So...no, I wouldn't hesitate to spread some more on the whole space or the selected spots. I guess in these instances, redoing the entire piece is easiest with the asphaltum process. Sorry.... A bit of a ramble as different ideas keep popping up!

[Raymond Chapman]

Thanks Old Man. We did the asphaltum thing and re-glued the whole area. It's in the chipping booth now...so, we'll see what happens.