I notice on the bottle of polyester resin I got that it says not to mix
the stuff in a waxed paper cup. It's in bold too, so it seems
important. Not only was that how I was going to mix it, but I was going
to lay the material on some wax paper so it won't get glued to the
floor. I have used 2 part epoxy in this fashion and it has worked well
(the epoxy cures and was too flexible, so I'm using polyester.). Does
wax react poorly with polyester resin?

On 11 Oct 2005 19:37:44 -0700, wrote:

I notice on the bottle of polyester resin I got that it says not to mix
the stuff in a waxed paper cup. It's in bold too, so it seems
important. Not only was that how I was going to mix it, but I was going
to lay the material on some wax paper so it won't get glued to the
floor. I have used 2 part epoxy in this fashion and it has worked well
(the epoxy cures and was too flexible, so I'm using polyester.). Does
wax react poorly with polyester resin?

One way of producing a polyester gel coat is adding wax. This holds
off the air from the surface, so it does not stay tacky.
Dissolved wax is not the best ingredient for other layers however.

Brian Whatcott

There are two types of Polyester resin for fiberglass:
1. Laminating resin .... contains wax that comes to the surface when
curing so that the next layer fully bonds ... the wax is an 'air
inhibitor'. Laminating resins will always feel sticky to the touch
because of the wax. This wax is soluable in liquid polyester.
2. Finishing resin ... contains NO wax and when exposed to air while
curing forms a hard surface

What you have is probably finishing resin .... and any contact with wax
will change it.

So, you cant use wax anywhere near a finishing resin or you'll
contaminate it and begin to turn it into a laminating resin ...... but
you can use SARAN to keep it sticking where you dont want it to.

In article .com,
wrote:

I notice on the bottle of polyester resin I got that it says not to mix
the stuff in a waxed paper cup. It's in bold too, so it seems
important. Not only was that how I was going to mix it, but I was going
to lay the material on some wax paper so it won't get glued to the
floor. I have used 2 part epoxy in this fashion and it has worked well
(the epoxy cures and was too flexible, so I'm using polyester.). Does
wax react poorly with polyester resin?

Rich Hampel wrote:

There are two types of Polyester resin for fiberglass:
1. Laminating resin .... contains wax that comes to the surface when
curing so that the next layer fully bonds ... the wax is an 'air
inhibitor'. Laminating resins will always feel sticky to the touch
because of the wax. This wax is soluable in liquid polyester.
2. Finishing resin ... contains NO wax and when exposed to air while
curing forms a hard surface

What you have is probably finishing resin .... and any contact with wax
will change it.

So, you cant use wax anywhere near a finishing resin or you'll
contaminate it and begin to turn it into a laminating resin ...... but
you can use SARAN to keep it sticking where you dont want it to.

Beg Pardon. I belive you have got it the wrong way round. Last time I
looked at a can of wax in styrene it was to be added to gelcoat or even
laminating resin for the final coat if it was to harden in contact with
air without leaving a tacky surface and was NOT for laminating.

Anyway the OP should just go out and buy a big pack of cheap
PolyPropylene cups. That's 5 or PP in the recycling triangle on the
base. Suitable for nearly all paints ,resins, glues and solvents you are
likely to meet working on boats.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL:
'Stingo' Albacore #1554 - 15' Early 60's, Uffa Fox designed,
All varnished hot moulded wooden racing dinghy.

The solvents in polyester resin dissolves wax and the wax prevents bonding
of the next coat. It will eat Styrofoam cups too. Been there, done that,
got the mess on the shop floor to prove it. I eat a lot of cream cheese and
Jell-O pudding just for the plastic cups. :-)

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

wrote in message
oups.com...
I notice on the bottle of polyester resin I got that it says not to mix
the stuff in a waxed paper cup. It's in bold too, so it seems
important. Not only was that how I was going to mix it, but I was going
to lay the material on some wax paper so it won't get glued to the
floor. I have used 2 part epoxy in this fashion and it has worked well
(the epoxy cures and was too flexible, so I'm using polyester.). Does
wax react poorly with polyester resin?

So PVDC will peel right off?

So PVDC will peel right off?

I don't know that I would risk it with household Saran wrap. Being very
thin it can tear and leave little bits that are the devil to get off. I
made that mistake with a Saran peelply that was to thin. I needed a lot of
stretch for that particular part. It stretched fine but came off in strips.
Nylon would have been much better.

I generally don't like films as a curing barrier for polyester. A wax
sanding aid additive works better and doesn't disturb the surface.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

So I don't know who to listen to. Will wax paper leave me with a
unsuitably sticky surface when cured?
Wax paper would be easier for me to work with than saran.

wrote:

So I don't know who to listen to. Will wax paper leave me with a
unsuitably sticky surface when cured?
Wax paper would be easier for me to work with than saran.


I have used waxed paper with epoxy and with polyester. It leaves a
smooth, well cured surface possibly "contaminated" with a tiny trace
of wax. It releases easily, like polyethelene sheeting. I would of
course de wax with acetone if I was to laminate over it.

Terry K

The basic chemical principle is that oxygen greatly slows the rate that
polyester resin cures or "polymerizes" (the molecules link up in long
tangled strings).

The styrene in the resin will dissolve the wax off the paper. As the resin
polymerizes it squeezes the wax back out to the surface forming a thin
film. This film of wax prevents oxygen from reaching the surface so it
cures completely and becomes almost chemically inert. If it is the last
coat that is what you want it do. You can even buy "sanding aids" that are
a solution of wax in styrene to add to the pot while mixing to promote a
hard finish.

However, if you are laying another coat you don't want that. The next coat
will only be mechanically bonded because the polymer strings can't link up
to the strings in the first coat. As polyester is not a very good adhesive
mechanical bonds are not very strong.

OTOH,as long as the resin is exposed to oxygen the molecules at the surface
don't complete the link up so it does not cure completely and remains
chemically active. The next layer of resin will then be able to chemically
link up to the first layer making the whole lay-up a monolithic mass. It
will eventually cure without wax but as long as the next coat goes on within
a few days it will form the chemical bond.

In other words, if you are working with the last coat polyester can (and
should) be exposed to wax. If another coat of polyester will be laid on
top, avoid wax.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

wrote in message
oups.com...
So I don't know who to listen to. Will wax paper leave me with a
unsuitably sticky surface when cured?
Wax paper would be easier for me to work with than saran.