Do GRP hardeners (catalysts) vary in strength

[DavidJ]

Hi
Just doing a spot of GRP repair (internal not particularly visible) I have the resin from Sealine but they won't sell the hardener. I've bought a kit (in Spain) (West System Resin and Hardener)which says to mix in the ratio of 5:1 by either weight or volume.
From an excellent previous posting on GRP repairs it suggests a 2% ratio.
Any ideas why the difference between 2% and 20% , can the hardener be different strengths, what should I use?
For those in the know the hardener says it contains Phenol, Triethylenetetramine, and Tetraethylenepentamine and I notice it's made by Wessex Resins in Romsey

 

[boatbuilder]

You've got the wrong stuff. To catalise polyester you need something like butonox. What you have is epoxy wich is not copaable.
Butonox is a methl ethate ketone peroxide.and is used at about 2% in polyester.
West is used at 5.1 resin to hardner.
You cant mix the two.

 

[DavidJ]

Thanks boatbuilder. This week on the boat has been a series of blunders and it sounds like I was going to continue the trend. Much appreciated.

 

[boatbuilder]

If you need catalyst then just go to a local boat builder every bodys allways got loads . Make up a test mix at 2% and see how you go

 

[DavidJ]

will do, thanks

 

[Alrob]

I am no expert but are you sure its not the colour pigment you have from sealine which you mix with clear gelcoat

 

[boatbuilder]

Good point.

 

[DavidJ]

[ QUOTE ]
I am no expert but are you sure its not the colour pigment you have from sealine which you mix with clear gelcoat

[/ QUOTE ]
hmmmmm!

 

[boatbuilder]

If it is gellcoat then 2% catalyst. /forums/images/graemlins/laugh.gif

 

[jfm]

Agree all the other comments ref 2%, and remeber (as you are in warm climes ) it is very temperatoure sensitive so use small pot amount or keep catalyst qty to lower end of range

One extra thing though - it sounds like you are doing internal repairs on the non gelcoat side of things, right? In which case, if the repair is important, you'd be better using epoxy not polyester resin. Epoxy is generally used in repairs becuase it sticks better to old polyester.

If your repair isn't mission critical and you dont need maximum strength then no need to worry, just prepare the surfaces well and use polyester