Unexpectedly, the temperature that
night set record low temps. The next morning the bogg was firm-ish
but the painted on layer was still gel. I attributed the difference
in hardness to the exothermic heat (warmth generated by the reaction
of the materials) that would have been developed by the bogg
layer due to it's thickness and the fact the painted on layer
had less thickness to generate it. So I wiped down the bogg to
remove the 'amine blush' and since the other layer was still
wet I thought I would take advantage of the opportunity
to put another layer of resin over it all.
Troubles
it wasn't going off! What
happened? In spite of the day time temperatures the first layer
remained gel and was not effectively 'tying' the substrate to
the subsequent layer. A day or two to set in these conditions
seemed plausible but after several days it was becoming obvious
it was more than that. I did a test with the resin used. Mixed
one pot with the hardener (medium) I had used on
the first roll on layer (I had used a different resin/hardener
on the bogg), then another with a different bottle of hardener,
then another using the hardener for the other type of resin(in
case I mixed them up). The latter two were hard by that evening
but not the first pot, it was still loose gel. Two days later
the first pot was better but still rubbery. Mystery solved, bad
hardener. Putting my test panel in the sun for a couple days
really helped harden the rubbery stuff so
I knocked up
a frame for the hull and Kay and I rolled it out the shed, through
the big tent, and out into the yard to get what winter sun we
could through the forest that is the yard. It's going slow but
progressing and that is where we are for now.
If it doesn't set to satisfaction then
I get out the heat gun and go to work, scaping off every inch
of the hull and washing it down with acetone. Sure glad Kay is
running the paper
I need the time!
Again, lesson learnt? If in doubt, test.
If not in doubt, you should be, test anyway. The hardener was
17 months old, kept covered in the original container and had
been properly stored indoors. I can't wait to get to the vinylester
part of the project!
I am looking at plywood for bulkheads,
having picked up some good tips by looking at a few other boats
and talking with Leon of the $21K cat
. Still undecided about decks but possibly for them and other
parts, the Polycore panels that Ian is using for his motor sailor
being built in Maryborough seem interesting. See
TCP # 36 |