how do you prevent this? surfacing agent? ethanol rub before hot coat? is it caused by dust?
kirk
i was just reading the sticky on eps and epoxy and it says that using additive f eliminates many problems including fish eyes in hot coats. Not sure if you have to be using a certain type of epoxy to be able to use additive f, but check out the sticky…its near the top, under the additive f section.
some sandpaper is coated with a soap-like substance (zinc stearate or similar) to make “non-clog” sandpaper. Can cause fisheyes in lots of finishes. Not sure if it causes this problem with epoxy, but it might…
…can someone PLEASE post a photo of what a “fisheye” [in a resin coat on a surfboard] looks like ?
I have no idea what you are typing about .
cheers !
ben
I assume by fisheye you mean a bubble or fifty.
Sealing should reduce these.
Lam/hotcoat in a dropping temperature reduces these (and a climbing temperature env increases them).
“Whipping” your epoxy instead of just mixing it well may cause in them.
Don’t think epoxy blush causes them, but it should be removed in any case before hotcoating.
Hotcoating a lam surface that isn’t properly clean will very likely cause this.
Just my 2c!
a fish eye is more like a crater than a bubble. Surface tension issues usually caused by contaminants…
Wow, I was just going to post a question about the sandpaper coating and epoxy compatibility. There was a thread about it awhile back but I couldn’t find it in the archives. Do you remember what type of sandpaper to avoid? Garnet? Aluminum oxide? Also, do you think it would cause problems with the foam to lam bond?
i got the same thing on my first epoxy…just be sure to keep everything clean…and i found that it helps to thin the epoxy a bit with a cap or two of denatured alcohol.
Quote:
Surface tension issues usually caused by contaminants…
… and high humidity (WHY oh why do I always accidently schedule hotcoating during steamy summer nights?)
Automotive paints are also very sensitive to dust and humidity… that is why the rooms in which cars are painted are well filtered and humidity-controlled.
Ah. Gotcha KM.
yeah, cleanliness is next to godleiness - always figured that was gonna be real important in compsands anyway 
Tnx.
Fingerprints cause most blemishes, you generally see these in groups of 3 or 4, especially close to the rails where you would pick the board up.
Can you post a piccie?
…love the google ads at the bottom of THIS page !!
Here’s a pic, since I now know what they are. At least them showing up on a ding repair.
[img_assist|nid=1049663|title=Fish Eye|desc=|link=none|align=left|width=640|height=428]
the pic of the ding repair will look the same if you try to hotcoat after poscha pen or latex paint work, a light sanding will stop most of it.
The culprit Keith mentions is 'stearated' sandpaper. If you Google it, there are stories of problems in the woodworking and painting trades.
I like to use Coleman fuel (white gas) to remove any old wax before sanding. Change your sandpaper and avoid holding the board with your bare hand while sanding helps too.
Before glossing with any resin I wear gloves and sand. When taping off an apron I wear gloves too.
I know a guy who wipes down his epoxy lam coats with Xylene before fill coating... not sure on toxicity issues and don't recommend it for that reason. He claims it gives cleaner fill coats.
before I hotcoat i’ll wipe the board down with denatured alcohol. make sure you use a new clean paper towel and gloves. By doing this I have cured all fisheye type problems I have had with epoxy.
This might be only for Fiberglass Hawaii users, since I never used Resin Research.
Don’t use any surfacing agent in your laminations. Why do you want anything that might interfere with future coats bonding?
Don’t sand laminations, other than laps, and then only the high spots. Why do you want to damage the fiberglass cloth? You can turn 4 oz into 1 oz really fast by sanding it.
Use the Thin and Fast hardener for most hot coats. You can use the Thick and Fast if you have really ugly laps, but hopefully you got them down tight. The thick leaves really ugly brush strokes. The thin doesn’t.
Only use surfacing agent on your final coat. Especially if you use tints. Otherwise you end up with an uneven ghosting.
So I just delt with a massive fish eye problem. There must have been 200 little dimples in the bottom and 100 or more on the top of the board.
Epoxy.
I will explain the problem and then my fortunate fix.
I live on the east coast. Summer time tons of humidity.
I overhandled the board with bare hands. A result of feeling like I had lowered the rocker too much and “needed” to look at it over and over again to judge If I had just wasted a ton of time and money. (of course I pressed on)
I work out of a single garage bay and it’s dusty. Like, I barely sweep it out between shaping and glassing. And it the summer the florecent side lights attract bugs which attract spiders which make webs that hold dust. (awesome right?)
I was also experimenting with lowering my harderner to resin ratio. ( I always seem to end up with left over resin and it irks me.)
Anyway the board seemed to be glassing up fine in the high heat. Would not recomend lowering hardner in the cold.
I get to the hot coat and lay it on very thin. In order to reduce weight I also wanted to try and keep the hot coat lean. Not worried if I touched the first layer of glass.
I freaked a bit when I saw all of the fish eyes. I had never really experienced this before. I started doing wheelies with the sander 80 grit to get them down. (rolling it up on edge to kick the dust out) It was nuts! The fish eyes were skipping and the dust was flying off the board and they weren’t coming down! Additionally, the board’s hot coat was staying strong. Too strong for the amount of pressure I was putting on the sander. I should have been grinding though to the foam but it wasn’t. I was just skipping over the surface. And still the dust flew. I didn’t understand. ( I started soft but got firmer and firmer the more frustrated I got…ready to do massive repair work if necessary.) The disk slanted at 30 degrees and flying I was sweating and waiting for it to grind through…
I found out I had sterated sandpaper. Crazy…It wasn’t letting the grit get into the pock like craters. (I’m pissed and dejected…The board should ride fine…but it looks horrible)
I call my buddy to tell him I may have to remake his board. (he was cool about it but I’m out $200 in materials plus the time and effort)
The next day I search through my box of sandpaper and pull out the 220 grit…Dry, clean, sheet of non sterated. I cut the 8" disk. Shaking my head like…whatever. Let’s give it a shot.
I was about to re-hotcoat with a thin layer and try again…but first lets try a higher grit and see what happens.
Holy crap they are coming down! And they are coming down with ease. The non sterated (coated) sandpaper and higher grit is smoothing the whole thing down. Nice and easy…just like it’s supposed to do. Then to the wet hand sand with 400 and 600 and a blast with the wet buffer with mcguires car polish. (green junk) and the board looks fine.
Here’s the thing. I did everything wrong.
High humidity
over handled the board with bare hands
dusty environment that contaminated the coats.
lowered hardner to epoxy ratios ( mixed really well though)
In the end…It was QUALITY SANDPAPER that was NON sterated that saved the day.
And switching to a higher grit (220) that allowed me to cleanly wipe those fisheyes away.
[img_assist|nid=1075543|title=used to have fish eyes but quality sand paper saved the day|desc=|link=none|align=left|width=598|height=790]
Nice save! I especially like the board on the right.