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Fisheyes
By:Pete Rudie
Date: 3/4/1999, 11:51 pm
In Response To: Re: Raka Epoxies (Stan Heeres)

> YES. When I built the strip canoe, I noticed the fisheyes, but just had
> enough epoxy on the canoe to be able to sand it down. It was later that I
> read on the net somewhere that the possible cause for them was improper
> mixing. Don't get me wrong, I mixed what I thought was a long time (the
> length everyone said). The post said to mixed longer. On our two kayaks, I
> have mixed longer and the fisheyes are gone.

Hard to say now, but you may be confusing causation with coincidence. Fisheyes are caused by surface tension in the coating bridging it around a contaminant. This is not the same as a pinhole, which is caused by an air bubble trapped in the film during cure. Since there is no chemical incompatibility between the resin and hardener, incomplete mixing would not cause fisheyes. It could cause soft spots or general incomplete cure, but I suspect that your fisheyes were caused by something in the working environment of which you were unaware. They are almost always caused by droplets of an oil-based substance, which may be floating around in the air from use of aerosols, honing oil left on plane blades, or similar contaminants that can get into HVAC ducts and circulate randomly over time. A quick wash with TSP (trisodium phosphate, or one of its eco-age successors) and several rinses with clean water will eliminate any chance of this type of problem.

Don't misunderstand about mixing, though - complete mixing is essential. Nearly all epoxy problems are caused by improper metering and mixing. Industrial polymer manufacturers recommend power mixing for no less than 2 minutes. Even for small batches this is important. I sometimes use batches as small as 15 cc, mixed in a plastic medicine dose cup from the drug store. I have a 1/4" dowel with 4 short wood screws inserted radially at one end, chucked in a VSR drill, and I mix for 2 minutes, scraping the sides 3 times during the process. It seems like a lot of trouble, but really it avoids a lot of trouble. There was this one time when my mix man screwed up on a 40,000 sq. ft. floor...

Messages In This Thread

Raka Epoxies
Chris C. -- 3/4/1999, 7:39 am
Re: Raka Epoxies
Stan Heeres -- 3/4/1999, 12:32 pm
Re: Raka Epoxies
Robert S -- 3/4/1999, 9:52 pm
Re: Raka Epoxies
Stan Heeres -- 3/4/1999, 10:56 pm
Re: Raka Epoxies
Roger Donahe -- 3/5/1999, 10:25 am
Re: Raka Epoxies
Stan Heeres -- 3/5/1999, 12:09 pm
Re: Raka Epoxies
Shawn Baker -- 3/4/1999, 12:41 pm
Re: Raka Epoxies
Stan Heeres -- 3/4/1999, 11:00 pm
Fisheyes
Pete Rudie -- 3/4/1999, 11:51 pm
Re: Raka Epoxies
Don Beale -- 3/4/1999, 12:16 pm
Re: Raka Epoxies
Rick S. -- 3/4/1999, 11:30 am
Re: Raka Epoxies
Stan Heeres -- 3/4/1999, 12:33 pm
Re: Raka Epoxies
Rick S. -- 3/4/1999, 2:26 pm
Re: Raka Epoxies
Rick S. -- 3/4/1999, 3:33 pm
Re: Raka Epoxies/Glassing Inside?
Shawn Baker -- 3/4/1999, 10:37 am
Re: Raka Epoxies
Jay Babina -- 3/4/1999, 9:15 am