Hi 

@VVS

With your method of using heatshrink tubing you start off wrapping a relatively cold Aluminium mandrel. then heating the entire thing to a high temperature (to activate the heatshrink tubing/tape you will be well above 100 degrees)

The tubing shrinks, and the Alu mandrel expands (more than you would think)!, and since both shrink tape and especially the tubing is elastic, it will keep a tight wrap on the CF/resin as the mandrel cools down, keeping the CF tube tightly pressed against the mandrel. Which is all good, from a curing point of view, but the heat also deteriorates the thin layers of wax or chem release, and may distort the combination of release film and wax/release to the point where it locks the composite into any microscopic imperfection in the mandrel.

It is quite possible that cooling the mandrel will not shrink it enough to have any effect on the CF tube, a 1 mm tube will still be a bit elastic on the circumference, and so it just stays attached to the mandrel.

As I said, I think the vaseline works because it forms a thicker layer, and in effect also "lubricates" the inner surface of the release-film, making it possible to slide the tube off the mandrel, wax or chem-lease does not have that "lubricating" effect.

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