Steve Maskery":21to1so6 said:
Richard, I've been thinking about this.
Whilst I see exactly how this helps, I don't see how it is any better than the more usually practice of having a top caul over the work. I mean, how is having a pyramid of three (say) smaller size plates over the top more effective than having just one?
It seems to help apply pressure in the middle of the panel first, then the pressure spreads from there towards the panel edges. I've no scientific or engineering proof that this is actually what happens, but back in the 70s/80s when I used a two platen Interwood press with a very stretchy black rubber membrane (easily puncture too by the way), and a heated hood that rolled from one side to the other, this method became the default technique for us after some disasters without a stack of boards because the improved results spoke for themselves. I simply carried the technique forward into the more modern vac presses and vac bags reckoning the same thing would apply with with those system too.
I sometimes go along with the motto of "If it ain't broke, don't fix it", and this is one of those cases. Of course I could just be opening my mouth and letting my belly rumble to no good purpose, and someone might be along soon to show just how wet I am about the topic. Slainte.