GL: Great-Loop Digest, Vol 62, Issue 2 fuel tanks

[Dennis OConnor]

This is a discussion of improvements to the leaking tank patch described above..  It is not a criticism of the original author...
   
  Once the iron is hot flushed, and clean and dry  - as described - then you inhibit the rust with rust convertor... Available at any auto body supply store, just brush it on generously...  Let that go overnight, then rinse 3 times with plain water, vacuum out between rinses, then run a blower in the tanks until dry...
  After that you wipe the areas to be epoxied with solvent - acetone is best -  Wear an air supply respirator when doing that and have a good air supply blowing through the tank to avoid reaching an explosive concentration of fumes in the tank, or the bilge...  Do not pour the acetone into the tank, just wet the rags...  This is highly flammable, so use your head.. No ignition sources... Unplug the  boat from shore power... Disconnect the positive terminal on the house batteries and the engine battery... Turn off everything...
   
  There is nothing special about ceramic powder being suspended in the epoxy; to stiffen the epoxy so it doesn't run, microballoons will work. Do not use talc or any absorbant filler...  West System dealers will have everything you need...  System 3 is a good source also... <there is nothing wrong with using ceramic powder, however>
  When laying down multiple coats with epoxy, do not let the previous coating cure to the hard state... When each coat just reaches the jelly/sticky stage lay the next coat over top so that the new layer chemically bonds into a single layer..  This is 40 minutes to 3 hours between coats depending on temperature and how 'hot' the hardner is...
  Paint the final coat of epoxy on without any fillers for the best chance of an absolute seal against pin holes...
  One cured, epoxy is impervious and does not have the reactive ends of the epoxide molecules available to polymerize with the next coat; you wind up with separate coats of epoxy in unbonded layers...  Not necessarily a fatal defect, but one that is easy to avoid...  You could use peel ply between layers of cured epoxy, but that is unnecessary expense...
   
  Using an epoxy coating will extend the life of steel tanks.. However, eventually moisture will wick between the expoxy and the steel, oxidize the iron molecules, and lift the epoxy layer off...  It is just the way it works - water is the universal solvent... But you will extend the life of the tanks, maybe until it is the next owners problem...
   
  Anyway, just suggestions from an old boat builder...
   
  denny

       
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