Pete Verdon wrote:
I've just about finished my first "A Pack" of West System epoxy, and
since my Dad was passing by the shop, that's only open when I'm at work,
I asked him to pick up more of the same. He came back with a pack of SP.

I presume this is pretty similar, but is it identical? I've got used to
the handling characteristics of the West stuff now. I'll also want to
swap the measuring pumps over from the old containers to the new - will
they a) fit the thread and b) avoid any undesirable reactions as the new
product meets the old in the pump?


Dunno... but... know some people who might know some people...

x-posted.

Andy

Andy Champ wrote:
Pete Verdon wrote:
I've just about finished my first "A Pack" of West System epoxy, and
since my Dad was passing by the shop, that's only open when I'm at
work, I asked him to pick up more of the same. He came back with a
pack of SP.

I presume this is pretty similar, but is it identical? I've got used
to the handling characteristics of the West stuff now. I'll also want
to swap the measuring pumps over from the old containers to the new -
will they a) fit the thread and b) avoid any undesirable reactions as
the new product meets the old in the pump?


Dunno... but... know some people who might know some people...

x-posted.

Andy

What's "SP" - a different brand?
If so, then it's not a good idea to use one brand of resin with another
brand of hardener. Even if the "part A" was formulated using the same
type of base commodity resin, the maker may add different reactive
diluents etc to adjust viscosity,or they may use a completely different
resin type, and that changes the ratio for mixing.
And talking of mixing, then these two pack epoxies rely on correct
stoichiometric ratio to achieve maximum mechanical properties when cured
- the correct ratio is very important. Too much resin, and the epoxy
cures too soft/flexible. Too much hardener, then although the resin
seems to cure hard and a little faster than usual, there's unreacted
amine/amide left in the otherwise cured resin. That draws in water, so
in any case but especially below the waterline, it eventually goes
cheesy or causes other major problems.
So if you bought matching packs of West System, and find out that you've
run out of one component before the other, then you need to ask yourself
why that might be.

If the "SP" is a different brand of resin, take it back and exchange it
for the right stuff.

On 11 Feb, 21:17, Andy Champ wrote:
Pete Verdon wrote:
I've just about finished my first "A Pack" of West System epoxy, and
since my Dad was passing by the shop, that's only open when I'm at work,
I asked him to pick up more of the same. He came back with a pack of SP.

I presume this is pretty similar, but is it identical? I've got used to
the handling characteristics of the West stuff now. I'll also want to
swap the measuring pumps over from the old containers to the new - will
they a) fit the thread and b) avoid any undesirable reactions as the new
product meets the old in the pump?

Dunno... but... know some people who might know some people...

x-posted.

Andy

I've used both on my plywood dinghy for repairs and found very little
difference between them other than colour, the Wests tends to be clear
and the SP is a little yellow. They both do a similar job in terms of
wetting out the wood . I've never used dispensers so can't answer that
question. I go by eye and it's always worked for me.

I've also coated my hull prior to putting Flag Copperquick* on it and
used both Wests and SP and once again so no difference at all in terms
of adhesion or coverage - the only difference being colour.

*Under no circumstances consider using Flag Copperquick. You end up
with a wonderfully burnished hull that turns slowly green and is very
attractive to both barnacles and the weed that grows on barnacles that
looks like blond pubic hair. I contacted Flag and they agreed that it
doesn't work and suggested I should be using their premium abrading
anti fouling.

Thanks you for the post.