Looking for advice on choice of best adhesive for GRP to Aluminium

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Jcorstorphine

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I am looking for some advice on selecting the best waterproof adhesive to bond 2 mm thick GRP to Aluminium.

I don't want an adhesive which is an immediate bond as the GRP section are 1.4 m x 0.3 M and I will need a few moments to correctly position them. I would also like the adhesive to be easy to spread so that it will even out with a small amount of pressure as the panels are quite big.

I am looking at using wood battens and G clamps to provide some compressive force but I need to be sure I don't deform the GRP panels as they are only 2 mm thick. I will be able to use some CS stainless screws in places to make sure it does not fall off and I will have a temporary batten at the bottom of the existing section to take the weight and provide a fixed vertical position.

The above is to bond GRP panels I have purchased to cover the existing lower aluminium panels on my motorhome which have become corroded in places.

Thanks
 
West Epoxy thickened well with glue powder as long as the ambient temperature is not too low, otherwise Sikaflex but 291 may not be the best choice, in either case go to the website for advice.
 
Jcorstorphine said:
I am looking for some advice on selecting the best waterproof adhesive to bond 2 mm thick GRP to Aluminium.

I don't want an adhesive which is an immediate bond as the GRP section are 1.4 m x 0.3 M and I will need a few moments to correctly position them. I would also like the adhesive to be easy to spread so that it will even out with a small amount of pressure as the panels are quite big.

I am looking at using wood battens and G clamps to provide some compressive force but I need to be sure I don't deform the GRP panels as they are only 2 mm thick. I will be able to use some CS stainless screws in places to make sure it does not fall off and I will have a temporary batten at the bottom of the existing section to take the weight and provide a fixed vertical position.

The above is to bond GRP panels I have purchased to cover the existing lower aluminium panels on my motorhome which have become corroded in places.

Thanks
Click to expand...


Sikaflex 252, a polyurethane structural adhesive similar to Sikaflex 292

http://www.uksealants.co.uk/downloads/Sikaflex-252-TDS.pdf


Sikaflex 512 Caravan adhesive and sealant.

http://www.uksealants.co.uk/downloads/Sikaflex-512-Technical-data-Sheet.pdf
 
On the basis that you are just trying to hide corrosion I'd use stickslike from any DIY store. If it's corroding now it will corrode even faster if you bodge / cover it up.
 
I'd be worried (maybe uneccessarily) that the clamping system would create an depressed image of itself in the finished panel. I recall from the Haynes caravan books that one favourite method was to park the van close to a brick wall and inflate a lifting bag between van and wall to press the panel into place evenly.

Rob.
 
Thanks Rob, very valid comment. The lifting bag and wall is not an option for me as don't have access to either but I think I can get close to an even pressure using a horizontal 70 x 40 batten with vertical sections every 70 mm. Plan would be to offer up the GRP and gently clamp with the baton then move it on a batten width and clamp again and so on. Other variation is to only apply adhesive in vertical strips that I can gently compress with the vertical battens.

Thanks to all for suggestions. All I need is a couple of dry days but not much sign of a good spell.
 
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