Baking secondary follow-up

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Original poster: "Coyle, Thomas M." <tcoyle@xxxxxxxxxxxxxxx>

I apologize for the couple-month-late reply on all of this - work has 
been getting crazy so I've had little time to do anything except read 
the interesting threads of late.

Thanks to everyone who made suggestions to my question about baking 
my polyurethaned secondary.

After taking everything into consideration, I stuck it in the oven. 
Someone made a suggestion along the lines of an hour at 150, an hour 
at 175, and 30 mins at 200. I did that, actually turning the oven off 
when it reached 200 and then letting the secondary sit in the oven 
overnight as it cooled.

Some comments and observations to address some of the questions that came back:

1) The stuff I used is "Minwax High Resin Polyurethane (Great for 
Floors!) Clear Gloss"

2) The directions say to apply a thin coat, allow to dry at least 4-6 
hours until the film is no longer tacky to the touch. Then, sand with 
220 grit sandpaper, remove dust, and apply second coat. Repeat as 
necessary. I, not being the RTFM type, applied a thick coat, didn't 
wait long enough, applied another thick coat, didn't wait long 
enough, and so on, about 7 times, which resulted in the outside 
curing nicely, and the inside being perpetually liquid, which started 
my whole question about how to fix the mess.

3) Baking WORKED! Well, for the most part. It still seems like the 
bottom layer is just a hair liquid, but overall, the thing is rock 
solid. As long as I don't go dropping it against the edge of tables 
or on concrete, I'll be fine.

4) Since the top layer had already become solid, air bubbles did rise 
up under that layer. However, the bubbles are large - I should have 
no problem taking them out with some easy sandpapering, and then 
doing one final recoat to fill in the holes.

5) Unfortunately, the length of the 1/8-inch-thick acrylic secondary 
(it's a 3x24 with about 930 turns of 22ga) caused it to sag under its 
own weight in the oven. Some simple research shows that acrylic 
starts deflecting with mild pressure at around 95C (=203F, 
coincidentally enough). I noticed this about 2 hours after turning 
the oven off, while it was still sitting there after having reached 
200F. When I noticed it, I turned the secondary 180 degrees (it was 
being held up by metal skewers) hoping it would sag back the other 
way. By morning, it did, nearly perfectly. There's still a 
barely-noticeable curve (probably a 100-foot radius circle) - I mean 
BARELY noticeable - but it shouldn't be a problem.

Thanks again for everyone's help!

Regards,

Tom

P.S. Next time I'm going to epoxy. If I have to wait until each coat 
dries before doing the next one, it'll be six weeks til I'm done. Of 
course, the debacle above itself cost me 6 weeks, so...