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 Topic: pin holes in aluminium
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13/10/2013 at 8:16pm
Location: Midlands
Outfit: Mondeo Avondale Gram
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If there is corrosion on the inside then you need to treat that otherwise it will continue to eat its way through.
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14/10/2013 at 8:05am
Location: Hants
Outfit: Fleetwood Heritage 640 EB & ML270
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You could bond some small plates (ally drinks can offcuts?) onto the inside of the damaged area with Sikaflex, then fair up the squeezed out stuff on the outside before it cures. Degrease it all with plenty of meths inside and out before you start and you should get a near invisible mend.
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14/10/2013 at 10:19pm
Location: Lancashire
Outfit: Caravan now Sold
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Quote: Originally posted by dksniper on 13/10/2013
I have purchased jb weld epoxy resin to do the repairs.Probably a silly question but are repairs best done on outside of skin?
Cheers Dave
osmosis causing the pin holes needs to be sealed from the inside if possible.use a alloy plate and plenty of sealer.
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the only silly question is the one you do not ask.
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15/10/2013 at 6:07pm
Location: Cambs
Outfit: Tin tent diddy tent BIG tent
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I'm not sure what you mean by the pin holes being caused by osmosis as I can not imagine osmosis happening through an impermeable membrane such as aluminium. Maybe I am missing something but I had always understood that the aluminium corrosion was a form of galvanic action due to water on the unprotected surface setting up a localised galvanic cell normally in the vicinity of a steel nail or staple.
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'A sure cure for sea-sickness is to sit under a tree'
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16/10/2013 at 10:09am
Location: Lancashire
Outfit: Caravan now Sold
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I'm not sure what you mean by the pin holes being caused by osmosis as I can not imagine osmosis happening through an impermeable membrane such as aluminium yes any long standing damp on the inside of the van will look for a way out,hence the pin holes.
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the only silly question is the one you do not ask.
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16/10/2013 at 12:41pm
Location: Cambs
Outfit: Tin tent diddy tent BIG tent
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That is not osmosis - osmosis is the flow of a solvent (could be water) through a semi permeable membrane to equalise the osmotic pressure between two fluids. My memory of entropy and thermal dynamics is a bit faded but that is a basic summary of what happens.
I'm 99% sure the pin holes are caused by galvanic action but if I get a few minutes I will double check. Assuming galvanic action the only way to stop it is to prevent a cell forming and the obvious way is to exclude water and then as Mattlad says above the oxide of aluminium will form a protective layer on the surface.
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'A sure cure for sea-sickness is to sit under a tree'
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