Silicone sealant WITHOUT acetic acid

Several people have reported problems with corrosion as a result of using silicone sealant in small Stirling cycle engines.

The common RTV silicones do use acetic acid as part of their curing method.

This has been a problem in electronics assys for some time, with the acid corroding conductors and leadwires, and as a result the silicone companies developed "neutral cure" or "electronics grade" RTV sealant with no acetic acid cure.

I am not sure about availability in the UK but in North America it was marketed as Dow 737 neutral cure RTV sealant.

Maybe Radio Spares or Farnells carry it in UK. Digikey and Sayal Electronics both carry it in USA and Canada.

Good luck JD

Glaziers will sell you a more expensive 'rubberised' goo for sealed double glazing which I think is acid free. Used because some panels use metal spacers round the edge.

What you need is low modulus silicone. This is not the acetoxy high modulus type. It does take longer to cure but generally has better adhesive properties.

If you want mail order (or have a local outlet) try "Toolstation" product code 85598

Cheers

used this to reseal an alternator regulator after I replaced a faulty transistor -

**LINK**

John

Silicone sealants are either 'acetoxy cure' or 'neutral cure'. These are the key phrases to look out for when purchasing. To avoid the corrosion problems, use a neutral cure sealant. Screwfix and Toolstation sell neutral cure sealants.

When I went into a local builders merchant and asked for clear silicone they were one of the few that asked if I wanted the sealer or the adhesive versions. So depending on what will be done with it that may be worth bearing in mind. The glue types will give of acetic acid as they cure.

Taken over by a chain now so the person behind the counter probably wont have a clue. Moan over. There were a lot of smaller companies supply various trades round here and they are steadily disappearing.

John

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