Date: 12/6/2001, 10:34 pm
I mixed a small batch of MAS slow cure three nights ago, to coat glass edges on the tips of my new paddle.
I used half the batch on one side of the paddle blades, and let it cure overnight while the other half the batch was in the freezer. Then, last night, after looking carefully at the problem with the first half, I decided to put the second half on the other side of the paddle, and see if it did the same thing.
The first half, when I went out the following night ( last night) to finish the job, looked fine when I first looked at it - glass smooth and no bubbles. But when I touched it, it was as though there were a film of moisture on it - the moisture came off on my hand. No smell or oily feel to it. And as it came off, it left an 'orange-peel' effect - like small surface bubbles, uniformly sized at maybe .25 mm - about the size of the tip of a pin. I wiped the whole surface, and it all did the same thing. I set it aside thinking about it a few minutes, and then looked some more. I first thought it must have been a bad mix. But the epoxy had gone off- no gummy mess and I couldnt scratch it with a fingernail. Just this surface problem. So I decided to thaw the second half and use it. It's a small area and I figured if it were a real problem I'd just sand it down.
The second half - of the same mix - went off fine. No surface wierdness. And it spent the night in the freezer.
I can think of two possible explanations. My shop is quite cold - 40 degress unless I light a fire, which I only do while I'm working. Also, there has been a lot of rain and I do have higher humidity in there than I'd like. But the second half of the same batch went off OK, and I'd think if it were humidity I'd have the same result.
The other POSSIBILITY - I am not sayin this happend, or that it didnt - just that it's a possibility - is that I sprayed a little bit of laquer finish on another little project, which would have been about 5 feet away from one end of the paddle - 10 feet or so from the other end. If that's true, then perhaps the laquer vapor interfered with the surface of the epoxy somehow? I'd think that would have has a lesser effect at the end of the paddle further away. If I did spray, I did not get any overspray anywhere near the epoxy. It would have been evaporative fumes only. I definately didnt spray last night, and that half went off OK, so perhaps it's more than a slight possibility....
In any case I dont think it's too bad, it's thick enough to sand fair anyway. It's just wierd.