Suggest your call a resin manufacturer directly.

My 'poor memory' has it that after the oil crisis of the mid seventies
there was a change of formulation to include fire retardants .... thus
rendering the resin substrate chemically more permeable and reactive to
free water and water vapor ..... somewhere near or after 1978-79.

Also at that time (oil supply reduction from OPEC) also led the
fabricators to 'thin-out' the mass of resin in structure .... which
allows more water permeation into a resin-poor laminate.

And at and before that time fabricators (some more than others) used a
discontinuous lay-up process .... essentially allowing successive
layers of laminate to partly 'cure' before applying the next layer,
etc.

The EPA really came down hard on the chemical (resin) industry in the
mid 80s versus volatile emissions (especially in eco-nazi areas such a
California, etc.) ... so there is another possible date of further
'degradation'. At that time the fire retardant formulations also
changed.

You might want to discuss this with a resin manufacturer to 'refine'
the details, etc.

The real answer is to what I perceive is your possible real question:
if a hull constructed during that time was adequately barrier coated
(few were) then the laminate of the old boat that youre looking at will
have minimal osmotic blistering and minimal hydrolysis (degradation due
to water contact) of the resin in the structural layers. However the
laws of entropy will eventually take effect ... and everything in the
universe will eventually fail and wear out. So if youre looking at an
old boat and want to know the long term integrity of the hulllaminate
structure, go to an owners group (Sailnet, etc.) and ask the specific
questions to those owners.

;-)



In article , Trent D.
Sanders wrote:

Does anyone out there know which year the EPA [or whatever the
bureaucracy was] made the boat builders change from the old "good"
fiberglass to the new "environmentally friendly" glass? I seem to
remember it being about 1972 [?].

T. Sanders
S/V Cimba