Any idea what is this blue stuff?

January 04, 2014, 11:54:31 am

I decided to clean out any rust in the rear bulkhead area and paint with Ospho before problems arise. I started by cutting off a 6" strip of the outer skin to expose the steel floor structure. I was expecting to see pieces of blue insulation board between the metal box beams. Instead, I found these hard-as-rock blue blobs (see photo).

My speculation is that these blobs were once the foam insulation. What could have done this? There are no signs of heat damage. Some type of chemical reaction?

Any speculation? Has anybody else seen this?

Re: Any idea what is this blue stuff?

Reply #1 – January 04, 2014, 12:00:51 pm

Jim, that is melted polystyrene insulation that has been exposed to diesel or some other solvent. Where is your fuel tank in relation to this area? I saw more than my share of this upfront underneath the diesel and propane tanks when I did my bulkhead Project. A good replacement is polyurethane foam board insulation because that is not as susceptible to diesel. Although, acetone would eventually attack it. The Blue polystyrene rigid installation would melt almost immediately upon contact with acetone, and A little bit slower with diesel.
Don

Quote from: Jim McNeece – January 04, 2014, 11:54:31 am

I decided to clean out any rust in the rear bulkhead area and paint with Ospho before problems arise. I started by cutting off a 6" strip of the outer skin to expose the steel floor structure. I was expecting to see pieces of blue insulation board between the metal box beams. Instead, I found these hard-as-rock blue blobs (see photo).

My speculation is that these blobs were once the foam insulation. What could have done this? There are no signs of heat damage. Some type of chemical reaction?

Any speculation? Has anybody else seen this?

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