On Wednesday, 21 June 2017 12:02:20 UTC+1, Stephen wrote:
Hello,

I need to buy some glazing clips so that I can assemble a greenhouse.

I have used galvanised W clips in the past and one or two did rust
after some years, so I was wondering about buying stainless W clips
instead. What does the group think?

I also need the Z clips that allow you to put the top pane above the
lower one. I see you can buy these in aluminium or stainless steel. Is
one better than the other, or should I buy whichever is cheapest?

Thanks,
Stephen.

IME, aluminium glazing clips (w and z) beat stainless steel hands down. All it takes is a little scratch in the surface and ....

OTOH, have a couple of lean-to "growhouses". These are made entirely of aluminium and are polycarbonate glazed. I need to replace the poly panels but, to do so, need to unscrew fixings between the alu struts. I have tried everything I can think of from WD40 thru all sorts of "professional" things. I cannot shift a single screw. So I wonder if the "non-corroding" properties of aluminium are what they're made out to be!