This may be a little of topic, but I know that dewaxed shellac is considered
as an excellant sealer in between incompatible finishes. But would it seal
styrofoam adequetely enough to allow polyester resin to be applied over it?
As many of you may know resin will melt styrofoam and even cause it to burst
into flames. I can use urethane foam instead but I have a perfectly sized
styrofaom box that would save me a lot of build time. Anyone try this?
Thanks,
Gene
--
This message has been scanned by Norton Anti-virus software
Edwin,
You have made some very good points. I suppose that if in my initial post I
had said that a foam cup had burst into flames- no one would confuse that
with high grade building material foam. I will try to be more careful in
the future regarding that type of statement.
Gene
"Gene T" <[email protected]> wrote in message
news:[email protected]...
> This may be a little of topic, but I know that dewaxed shellac is
considered
> as an excellant sealer in between incompatible finishes. But would it
seal
> styrofoam adequetely enough to allow polyester resin to be applied over
it?
> As many of you may know resin will melt styrofoam and even cause it to
burst
> into flames. I can use urethane foam instead but I have a perfectly sized
> styrofaom box that would save me a lot of build time. Anyone try this?
> Thanks,
> Gene
>
> --
>
>
>
>
>
> This message has been scanned by Norton Anti-virus software
>
>
On Sun, 10 Oct 2004 00:08:18 GMT, "Gene T" <[email protected]>
wrote:
>A friend of mine was mixing up a batch of resin in a syrofoam cup and the
>cup did burst into flames and injure him. It's possible that he used too
>much catalyst and that type of extreme thermal reaction probaly wouldn't
>occur on a open surface.
Well _duh_ ! Yes, That's an excess of catalyst in the resin. Nothing
to do with polystyrene foam.
--
Smert' spamionam
Some shellac thinners contain MEK. I'd give the traditional check on a
piece of scrap, rather than experiment on my project.
Come to think, make it a small scrap to limit the fuel....
"Gene T" <[email protected]> wrote in message
news:[email protected]...
> This may be a little of topic, but I know that dewaxed shellac is
considered
> as an excellant sealer in between incompatible finishes. But would it
seal
> styrofoam adequetely enough to allow polyester resin to be applied over
it?
> As many of you may know resin will melt styrofoam and even cause it to
burst
> into flames. I can use urethane foam instead but I have a perfectly sized
> styrofaom box that would save me a lot of build time. Anyone try this?
> Thanks,
> Gene
>
> --
>
>
>
>
>
> This message has been scanned by Norton Anti-virus software
>
>
"Gene T" <[email protected]> wrote in message
> As many of you may know resin will melt styrofoam and even cause it to
> burst
> into flames.
Burst into flames? Have you ever seen that? What information do you have
of this?
I've been in the industry for 34 years,have every technical and safety
manual, have attended seminars, spoken with the chemists, etc., but have
never heard of polyester resin causing foam to burst into flames. You sure
have me curious as to where the facts of this come from.
First, you do not have a Styrofoam box. You have molded expandable
polystyrene. Styrofoam is Dow Chemical's registered trademark for extruded
polystyrene board.
As a barrier, you can get good results with a coat or two of latex paint.
Be sure there are no pinholes after the paint dries. I'd use two coats or
at least dab in to fill the voids..
Rather than resin, you can use most epoxies on the foam with good results.
Try the mixed epoxy on a scrap piece to be sure of the compatibility.
Polyester resin contains styrene, the solvent for expanded and extruded
polystyrene.
On Mon, 11 Oct 2004 04:23:04 GMT, "Gene T" <[email protected]>
wrote:
>Having said that, what would have made the cup catch on fire?
Unlike epoxy, curing polyester resin is a catalytic process. It's also
exothermic (generates heat). The reaction carries on at a rate
dependent on the amount of catalyst, so if you add too much in one go,
it can proceed at a furious rate. As polyester resin is also
flammable, and may have some other inflammable solvent in there as a
thinner, then it's a great fuel source. You know the rest.
I believe this most commonly happens in plants spraying catalysed
resin, such as the strand-chopper guns that spray both components onto
the inside of a mould. The resin is heavily thinned and heavily
catalysed. If you mix up a batch of resin then leave it in the pot for
too long (usually because the gun has a fibre jam) , it overheats.
--
Smert' spamionam
"Gene T" <[email protected]> wrote in message
news:[email protected]...
> Ed,
> I'm not trying to beat a dead horse. Having said that, what would have
> made
> the cup catch on fire? I have never had a foam cup catch fire on me
> before,
> unless I've tossed it into a campfire. So, what can I factually say
> happened? I'm not trying to be sarcastic..
> Gene
Burning resin would start the cup burning. As would any other burning
material. The real question is what started the resin burning? There may
have been too much catalyst, an open flame, etc. Once the resin, mostly
styrene monomer, starts, any flammable container will go with it. Could
have even been an explosion from his dust collector. ;)
My concern is that a mis-statement can cause people to think that the resin
in any form will cause eps foam to burst into flames. Styrene will melt at
190 degrees and will burn when contacted by an open flame. Modified grades
of material are used in home building and other applications that require a
fire retardant. Modified material will only burn in the presence of an open
flame and will go out when the flame is removed.
"Gene T" <[email protected]> wrote in message
news:S3%[email protected]...
> Edwin,
> A friend of mine was mixing up a batch of resin in a syrofoam cup and the
> cup did burst into flames and injure him. It's possible that he used too
> much catalyst and that type of extreme thermal reaction probaly wouldn't
> occur on a open surface.
Could have been many causes, such as smoking too. The resin itself is a
flammable product. Containing mostly styrene monomer, it has the ability
to burn. If it was to burn, it would start the foam cup on fire also. To
say the resin reacted with the eps foam is quite a stretch.
From: Ask A Scientist
http://www.newton.dep.anl.gov/askasci/eng99/eng99263.htm
My point is, I once bought a quart can of 100% styrene monomer
liquid. Without inhibitors, it would solidify in 10 seconds to 1 minute,
and get so hot
I would have to drop the bottle. "Hazardous polymerization" is even one of
the hazards listed on every MSDS chemical safety sheet, right after
flammability and such.
When you add "catalyst" to casting resin, it is really an oxidizer. It
uses up the
inhibitor, then what is left attacks a few double bonds, starting
polymerization.
Oxygen in air often acts as an accidental inhibitor. I think this is why
the surface of
some resins remains tacky, incompletely cured.
From a typical MSDS for polyester resin:
Health and Safety: Unsaturated PolyEster resin (UPE)
Base resin: polymer chains with reactive sites (50%)
Styrene: reactive diluent (50%)
volatile
flammable:
flash point 31°C
explosive limits 1.1-8.0%
NO SMOKING, no naked flames
Ed,
I'm not trying to beat a dead horse. Having said that, what would have made
the cup catch on fire? I have never had a foam cup catch fire on me before,
unless I've tossed it into a campfire. So, what can I factually say
happened? I'm not trying to be sarcastic..
Gene
"Gene T" <[email protected]> wrote in message
news:[email protected]...
> This may be a little of topic, but I know that dewaxed shellac is
considered
> as an excellant sealer in between incompatible finishes. But would it
seal
> styrofoam adequetely enough to allow polyester resin to be applied over
it?
> As many of you may know resin will melt styrofoam and even cause it to
burst
> into flames. I can use urethane foam instead but I have a perfectly sized
> styrofaom box that would save me a lot of build time. Anyone try this?
> Thanks,
> Gene
>
> --
>
>
>
>
>
> This message has been scanned by Norton Anti-virus software
>
>
"Old Nick" <[email protected]> wrote in message
>
> What I can't understand is why anyone would mix polyester in a styrene
> foam cup. Polyester resin _does_ eat styrene, which is why you asked
> the question.
They don't, they only try to ;)
I'm sure a lot of people just don't know the composition of the material and
the cup is cheap and handy so . . . . . . .
Edwin,
A friend of mine was mixing up a batch of resin in a syrofoam cup and the
cup did burst into flames and injure him. It's possible that he used too
much catalyst and that type of extreme thermal reaction probaly wouldn't
occur on a open surface.
I did consider using the epoxies but as you know they cost considerably more
that polyester resin. And pardon my ignorance in not knowing the
difference between Styrofoam and molded expandable polystyrene.
Thanks,
Gene
"Gene T" <[email protected]> wrote in message
news:[email protected]...
> This may be a little of topic, but I know that dewaxed shellac is
considered
> as an excellant sealer in between incompatible finishes. But would it
seal
> styrofoam adequetely enough to allow polyester resin to be applied over
it?
> As many of you may know resin will melt styrofoam and even cause it to
burst
> into flames. I can use urethane foam instead but I have a perfectly sized
> styrofaom box that would save me a lot of build time. Anyone try this?
> Thanks,
> Gene
>
> --
>
>
>
>
>
> This message has been scanned by Norton Anti-virus software
>
>
Gene T wrote:
> Ed,
> I'm not trying to beat a dead horse. Having said that, what would have
> made
> the cup catch on fire? I have never had a foam cup catch fire on me
> before,
> unless I've tossed it into a campfire. So, what can I factually say
> happened? I'm not trying to be sarcastic..
Just for general reference back when I first started working with fiberglass
I made the mistake of activating a quart can of polyester resin with a
little too much catalyst, then not using it before it started to cure. It
was burning merrily at one point. That was a steel can. My Dad and I were
both impressed--we didn't know that it would _do_ that.
> Gene
> "Gene T" <[email protected]> wrote in message
> news:[email protected]...
>> This may be a little of topic, but I know that dewaxed shellac is
> considered
>> as an excellant sealer in between incompatible finishes. But would it
> seal
>> styrofoam adequetely enough to allow polyester resin to be applied over
> it?
>> As many of you may know resin will melt styrofoam and even cause it to
> burst
>> into flames. I can use urethane foam instead but I have a perfectly
>> sized
>> styrofaom box that would save me a lot of build time. Anyone try this?
>> Thanks,
>> Gene
>>
>> --
>>
>>
>>
>>
>>
>> This message has been scanned by Norton Anti-virus software
>>
>>
--
--John
Reply to jclarke at ae tee tee global dot net
(was jclarke at eye bee em dot net)
On Mon, 11 Oct 2004 10:20:43 GMT, "Gene T" <[email protected]>
vaguely proposed a theory
......and in reply I say!:
remove ns from my header address to reply via email
>Edwin,
>You have made some very good points. I suppose that if in my initial post I
>had said that a foam cup had burst into flames- no one would confuse that
>with high grade building material foam. I will try to be more careful in
>the future regarding that type of statement.
>Gene
Perhaps you play with Edwin a little?....
I definitely understood you to say that polyester resin would cause
styrene to burst into flames, and because you placed it in the context
that you know polyester eats styrene (chemically), I understand
Edwin's questioning and think that he stated his case clearly enough.
I don't think building material has anything to do with it.
What I can't understand is why anyone would mix polyester in a styrene
foam cup. Polyester resin _does_ eat styrene, which is why you asked
the question.
*****************************************************
Have you noticed that people always run from what
they _need_ toward what they want?????
I wasn't looking to determine what caused the styrofoam cup to catch fire,
but It MAY be because my friend used too much catalyst. I never did ask him
how many drops he used. And he was not smoking nor was there any other open
flame around at the time.
Gene
"Gene T" <[email protected]> wrote in message
news:[email protected]...
> This may be a little of topic, but I know that dewaxed shellac is
considered
> as an excellant sealer in between incompatible finishes. But would it
seal
> styrofoam adequetely enough to allow polyester resin to be applied over
it?
> As many of you may know resin will melt styrofoam and even cause it to
burst
> into flames. I can use urethane foam instead but I have a perfectly sized
> styrofaom box that would save me a lot of build time. Anyone try this?
> Thanks,
> Gene
>
> --
>
>
>
>
>
> This message has been scanned by Norton Anti-virus software
>
>
"Gene T" <[email protected]> wrote in message
news:[email protected]...
>I wasn't looking to determine what caused the styrofoam cup to catch fire,
> but It MAY be because my friend used too much catalyst. I never did ask
> him
> how many drops he used. And he was not smoking nor was there any other
> open
> flame around at the time.
> Gene
> "Gene T" <[email protected]> wrote in message
>> As many of you may know resin will melt styrofoam and even cause it to
> burst
>> into flames.
OK, that MAY be true. But you made a statement about the resin causing the
foam bursting into flames that is unfounded. If people believe that, they
may not buy my product and I'm out of a job.
Better we should stick to FACTS
Ed
On Mon, 11 Oct 2004 13:22:51 GMT, "Edwin Pawlowski" <[email protected]>
vaguely proposed a theory
......and in reply I say!:
remove ns from my header address to reply via email
>
>"Old Nick" <[email protected]> wrote in message
>>
>> What I can't understand is why anyone would mix polyester in a styrene
>> foam cup. Polyester resin _does_ eat styrene, which is why you asked
>> the question.
>
>They don't, they only try to ;)
hmp-hmp. Ok then.....
>
>I'm sure a lot of people just don't know the composition of the material and
>the cup is cheap and handy so . . . . . . .
>
*****************************************************
Have you noticed that people always run from what
they _need_ toward what they want?????