Join Date: Feb 2000
Location: Annapolis, Md
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Moonie asked me to comment on my earlier post. Like most people who have been into boats for a while, at some point I became very concerned about the whole the blister issue. I began reading everything that I could lay my hands on which discussed the causes and cures for blistering. What became very apparent was that there were a whole range of causes for blistering, some fairly benign (such as poor adhesion between the gelcoat and the laminate) and some very dangerous to the overall structural integrity of the boat.
In this last category are issues which are directly related to the formulation of the resin or additives such as accelerators mixed into the resin by the boat manufacturer. These last set of causes vary from a slow loss of ductility in resins allowing micro fissuring, and a range of other causes which include continued chemical processes within the laminate.
According to my readings in this second case, there can be a variety of chemical reactions at work. In some cases there are larger than normal trace amounts of water soluble materials that are formed as the byproducts of the reaction or suspended in un-reacted resin.
In those cases these water soluble chemicals can react with the water to form acids or else leech out over time and leave the resin more pourous than it initially was thereby allowing water molecules to get further into the laminate and allowing hydrolysis and the formation of acidic fluid deeper in the laminate than it might form otherwise. This was cited as one possible cause of deep blistering occuring in an older boat which had not experienced blistering earlier.
In at least some of the articles that I read, heat was seen as posible cause of later onset blistering and deep blistering. In my reading, I came across several case studies that discussed boats that were taken blister free from cooler water to the tropics and immediately began to have blister problems. My recollection is that even small amounts of heat can cause an accellerated reaction of some of the previously unreacted resins thereby forming water solubles and or microfisuring within these portions of the laminate.
In some of the discussions that I read, as a part of the research, the blistering process was purposely accellerated by soaking the laminate in warm water.
I am not a chemist and have not actually done any primary research on these theories, so I personally cannot tell you whether these theories are accurate, but to the best of my recollection the articles where I read these theories were either based on practical experience for the most part appeared to be science based. If someone has a better source of information on the relationship between heat and blistering, I would certainly be interested in being corrected.
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Curmudgeon at Large- and rhinestone in the rough, sailing my Farr 11.6 on the Chesapeake Bay