Bedding Bronze Strike Plates

Any suggestions on what bedding compound to use to re-bed my bronze strike plates to my rub rail?

I know I’m three months late … after talking to a local ship’s carpenter, I’ve chosen to use Simson ISR 70-03, made by Bostik, as the bedding compound on Zygote’s new chainplates.

Bostik says:

ISR 70-03 is a good compromise between an
adhesive and a sealant. ISR 70-03 is suitable for
making elastic constructive joints, which also
require a high strength. ISR 70-03 is based on Silyl
Modified Polymer.

. Solvent, isocyanate- and PVC free.
. Very good UV-resistance and ageing
. In general good adhesion on several substrates
without the use of a primer.
. Permanent elastic within temperatures from –
40°C till +120°C.
. Neutral, odourless and fast curing.

Bostik has a technical data sheet on its Australian website (and very likely on its US website):


In Australia, Bostik does not distribute Simson ISR 70-03 to retail hardware stores.

The ISR apparently represents ‘industry special range’. So this modified silyl polymer sealant/adhesive is therefore distributed only to firms in various industries. It’s much used by auto repairers, particularly for sealing windscreens to rubber gaskets and so on. So auto glass repair shops are a source in Aus. It shows up on online retailers such as too.

A skin forms after about 10 minutes; that skin will accept paint. Cure/polymerization time depends on thickness. As a bedding compound and on a warm day, I reckon curing (and adhesion etc) is complete within one hour. Bostik reportedly does make a slow kick version, with the moniker Simson ISR 70-03 SSK; I’ve not seen it.

The minimum size is a caulking gun cartridge (290 ml). Nothing smaller so you need to work fast (and refrigerate a partly used cartridge).

Bostik also has Simson MSR 70-03 where the M represents Marine. According to the master ship’s carpenter who is my source, the Marine version is only different by fire retardant characteristic.

Bostik apparently bought Simson, a Netherlands firm, in 2008 so it could obtain the rights to this silyl polymer compound. And since then, shipwrights have been preferring Simson ISR 70-03 over older polysulfide and polyurethane bedding/caulking compounds. Supposedly far superior to 3M 5200, Sikaflex etc. My contact reckons that the original Netherlands firm, Simson, invented or developed modified silyl polymer.