Rich- Wow, thats an impressive amount of advice. I'm also in PA (just north of Philly)....can I bribe you and your varnish brush to help with a few cold ones
? I do have a large fan (36'') at one end of the greenhouse with vents at the other end. It pulls quite a bit of air through. Like you suggested, I have always heard to varnish early on low humidity mornings. However, the teak seems to be gassing and creating bubbles as the temp rises during the day. Would it make sense to coat after the "heat" of the day, as the wood contracts and less likely to create bubbles?
Like most first applied coatings HT will 'bubble up' when the wood gets hot. Best to do the 'spit' coat on a cool day; otherwise, wait until the coat is starting to 'kick' then just knock the bubbles down with a quick light swipe of a finger. HT if applied thick later on will fill those 'craters' - promise. You really dont have to be FUSSY with HT as you do with varnish as if applied thick will have great fill and leveling capabilities. You really dont have to worry about gloss die-back on the base coats so applying on the downside of the hot part of the day may help ..... but dont forget that the humidity rises then so the verticals may start sagging/running if the 'kick' time is greatly extended.
The only real problems with HT are erroneously putting on the base coats too thin and the potential to sag/run on the verticals. The worst potential problem is a rapidly rising very high humidity will almost totally stop the cure; in that rare occurance dont touch the coating but WAIT allow to start to cure, then 'slop' on another coat as soon as the humidity goes back down ... will aid in the curing/'kicking' of the 'bad' coat. This is a very rare occurrence but can happen.
Be aware that it may take a few weeks for HT to 'fade' into a proper clear amber hue .... it may initially look somewhat like 'butterscotch' (or worse, may look like butt-ugly cetol) for the first few weeks, but will quickly fade to a proper oil based varnish look.
As like a primo varnish job, you can after a month or two of curing, flat sand with 2000 or 3000 grit W&D and then either (bare hand) hand-rub with rottenstone & water or wet-sand and POWER BUFF (w/foam knobby pad) with 3M finese-it, then 3M Perfect-it .... and will then make a brand new Hinckley blush with envy. The heat from hand-rubbing, etc. is what produces that dazzling iridescent GLOW under varnish and will remove almost all the 'dust, etc. imperfections'.
Caution: dont sand down the 'base coat' unless *absolutely* necessary ... its the UV filters in the base coat that allows HT to last for 10-12+ years and you want LOTS of intact UV filter to prolong the life of the coating system.
Gang finishing .... nah, do it yourself until you experience and find the learning curve. HT is a FAST finish to apply. Once you get the 'hang', you'll be doing wet-on-wet in no time .... with the exception of the damn verticals and thats a problem with varnish too.