Resin/hardener ratio for Ripmax SP Epoxy?

[Justin Needham]

Hi.

 I have some old Ripmax SP resin and hardener. It is still OK enough for a gash job I have in mind, but I don't know the proper ratio.

 I've scoured the web but can't find the info. The quantities in the two pots don't give much away, it could be probably in 3:1 or 4:1. Does anyone still have instructions?

 Thanks

[Tim Mackey]

2 cm "worm" of hardener to 100ml of resin ... I think

[Justin Needham]

Thanks Timbo, but it's a two liquid set. Containers originally 392 gm and 108gm. I'm not sure the proper ratio would really be 3.62:1. Sounds unlikely.  Perhaps this is a 3:1 by weight mix, I don't know.

[Tim Mackey]

ah sorry...wrong one then

[Bruce Richards]

I have some and on  the box it says 3 parts resin to 1 part hardener.

[Andy Butler]

3 or 4 to one is usually the ratio for most resins. You will probably find that mixing the two together will give the right ratio by weight. It's not that critical - more hardener makes the finished resin set faster and harder but more brittle, less and the cure will be slower and the resin may stay flexible for some time. I use 5 minute epoxy a lot and vary the mix according to the properties I want.

[Justin Needham]

Thanks then Bruce and Andy!

Justin

[Bob Howard]

They did 2 types of SP resin.

 If it is SP113 (it probably is) then 3parts resin to 1part  hardener by volume.

 If it is SPX 5000, 5 parts resin to 2 parts hardener by volume OR  3:1 by weight

I notice some shops are stocking SP113 again - it was good stuff.

Re. Andy's suggestion about varying the mix :-

With polyester (the smelly stuff from Halfords), all of the chemicals neeeded to effect a full cure are in the resin. The so-called "Hardener" is only a catalyst, which sets off the chemical reaction. More catalyst, quicker cure.

With epoxy, each of the constituents contain a given quantity of the various chenmicals needed for a cure. If the ratio is not fairly accurate, some of the chemicals will remain in an uncured state. Too much hardener will result in a brittle mix with reduced strength, too little results in a cured resin a bit like cheese - soft & rubbery, again with little strength.

Nowadays I use Deluxe Products Aeropoxy for skinning, mouldings and joining foam wings.  If I remember rightly, the instruction leafelet suggests a maximum tolerance of 10% on the mix ratio (3:2 in this case), but I try to be spot on.

For building, my policy is to always use a slow epoxy. Not only does it give longer to work with, but the joint is far stronger. I sometime stir a  small amount of filler into the mix to add strength - either milled glass (from Great Planes) or Kevlar pulp (Fibretech).