Cumbersome

The Victorian crinolines shaping up. I took a quick break from door frame construction before lunch to assemble a little platform tower in the greenhouse so that I can work on the opening windows at the top. Still twelve triangles in need of covers not including the two panels that will open, and no door assembly to speak of. I looked for a supplier of window openers here in Japan, but as usual ridiculous prices put me off. I have ordered four from a company called Baylis in the UK. Something like four for the price of one at today's exchange rates.
If you happen be in the process of applying polythene or some other film to a similar structure allow me to expound a little on my findings. I bought seven 20m rolls of butyl tape 30mm wide and on the stiff corrugated panels I put a length of tape down the center of the spars and placed the cut panels, then covered the joint with another length of tape. I left the waxy cover strip on the tape to stop the furing strips from sticking to the joint cover tape, I should have thought to buy single sided tape for that job. We cut the polythene into triangles just larger than the size required. We applied the length of tape as before, but cut the backing strip down the center of the strip once it was in place and pealed away just enough of the backing to reveal the three corners of one triangular hole. After a few tries at that we also slit the backing tape about half way along and peeled back a patch at the center of each side. This allows you to stick the polythene at each corner and then at the center of each side after applying a little tension each time. Then you peel away each of the remaining strips while holding the polythene away from the tape and apply very slight tension before pressing those portions onto the sticky stuff.
You can see a White border around the bottom right triangle here, that is the backing strip on the half of the tape that hasn't yet been peeled off to attach any film. If you have another triangle to apply next door trim the excess polythene before preparing the other half of the strip of tape, or it will stick down and prevent the neighbour from getting to it's side of the tape.
Of course you could also use a lot of strips of narrower tape, etc, but this method was pretty economical on tape usage. And cutting the triangular shapes gives a pretty clean result especially with the thicker film we used.
I guess I will take a photo or two of that when I do the rest of the pieces.

There you go, this shows the polythene pressed on at the six points where the tape is exposed. Of course all this would be better if done from the bottom up in order to promote water shedding, but that would have meant some weird scaffolding design to avoid climbing on the dome. It is best not to try and stretch too much as it just causes a build up of wrinkles somewhere. If you have to rip the sheet off where there is something unsightly the band aid technique works best, just tug it of briskly and the butyl will give up it's grip on short sections without too much grudging. Trying to pull the stuff off gradually causes it to grab on like a limpet.