Re: [bolger] Re: Epoxy Cure
Hi, I work with chemicals, my experience is to discard all unsealed chemicals or expect bad results and onced opened soon thereafter, oxigen & humidity are main cause of spoilage. I have no personal experience with epoxy But, everything I've read on the subject says humidity causes this problem. Thanks, Mike
--- On Sat, 4/18/09, gbship <gbship@...> wrote:
> From: gbship <gbship@...>
> Subject: [bolger] Re: Epoxy Cure
> To:bolger@yahoogroups.com
> Date: Saturday, April 18, 2009, 3:42 AM
> Sometimes epoxy is must mysterious.
> There's a local commercial fishing boat supplier that sells
> an inexpensive 4:1 and 5:1 epoxy. I've had the same problem,
> mostly with the 4:1 stuff, mixed carefully and thickened
> with wood flour. The stuff set rubbery, although it did,
> after a few weeks, eventually harden. Unthickened, it will
> usually set tack free in a day or so, but may take several
> days to harden enough to sand. But sometimes it's quicker
> setting than others. Like you, humidity is my guess as the
> variable (since I live in Florida), but it's just a guess.
>
> Gary
>
> --- Inbolger@yahoogroups.com,
> "titanicslim" <titanicslim@...> wrote:
> >
> > --- Inbolger@yahoogroups.com,
> "Scott Webber" <scottw@> wrote:
> > >
> > > I've been working w/ the same 2:1 epoxy
> laminating resin for years.
> > > Always w/ success. A strange thing happened the
> other day. I made a
> > > small quantity from a gallon kit that I'd used
> most of recently.
> >
> > Hi, Scott
> >
> > The thing that I focus on, because of past epoxy
> difficulties I have experienced, is the epoxy itself.
> I stopped using System 3 because of it.
> >
> > After a situation that sounds a lot like yours I was
> told by a chemist that the component parts of epoxy, if left
> to sit a long time, may separate in the bottle so that the
> mixture of the two parts will not give you the required
> mixture. In other words, I wonder if one of
> your "A" or "B" bottles might have stratified and left you
> with an incomplete or imbalanced composition and given you a
> less-than-optimal final mixture.
> >
> > The contaminated Cab-o-sil may or may not be
> complicating the issue but, if you suspect it, leave it out
> of your tests or get a fresh batch.
> >
> > Dave
> >
>
>
>
>
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The epoxy was always mixed and then the thickener added. The reason I suspect humidity is it can vary greatly from day to day, especially in the spring and fall. I just used some of this leftover 4:1 to coat a hatch. It hardened okay in a day or so, but where the drips formed into drops, the epoxy is still soft after several days. Experience indicates it will eventually harden enough to sand. I think this is just a soft, slow hardening mix.
Gary
Gary
--- Inbolger@yahoogroups.com, "Jon & Wanda(Tink)" <windyjon@...> wrote:
>
> Querstion did you thickern before or after mixing the epoxy and hardner. If fillers are added before they prevent it from mixing thoroughly befor adding fillers they mix poorly and unevenly. Putting in the freezer to slow or stop the reaction is a poor practice and only realy works for a limited time and makes it weeker. Most epoxies should not be heated over 180 deg. F to cure it also can weaken the epoxy. Double boiling keeps it at the boiling point of water to melt componets that crystalize in container. This is when they are not mixed so the reaction is not effected when it is cooled and remixed. Simply not steiring enough when mixing or some unmiked at the edges of mixing pot can also interfear with a good reaction. A little of conponets A or B left in a juge can alow some of the chemicals evaperate into the air space throwing off the chemistry. Fuller or full jugs will last longer if stored in a cooler place. I store mine in the laundry room with the pumps wraped up in a ziplock baggy. It stays normaly at about 65 deg. and the baggy catches any drips if the temp fluctuates very much. Do any of these things sound like they may be the posible problem.
> Hope that helps. In humid areas for glassing and encapsolating try a Cycloaliphatic epoxy. It will not blush and humidity is not a problem with it. I have used a lot of it from this sorce and there are others.
>http://www.jgreer.com/
>
> Jon
>
> --- Inbolger@yahoogroups.com, "gbship" <gbship@> wrote:
> >
> > Sometimes epoxy is must mysterious. There's a local commercial fishing boat supplier that sells an inexpensive 4:1 and 5:1 epoxy. I've had the same problem, mostly with the 4:1 stuff, mixed carefully and thickened with wood flour. The stuff set rubbery, although it did, after a few weeks, eventually harden. Unthickened, it will usually set tack free in a day or so, but may take several days to harden enough to sand. But sometimes it's quicker setting than others. Like you, humidity is my guess as the variable (since I live in Florida), but it's just a guess.
> >
> > Gary
>
What brand of 1:1 epoxy do you use? I am always interested in trying something different.
Chris
Chris
--- Inbolger@yahoogroups.com, Bruce Hallman <bruce@...> wrote:
>
> On Fri, Apr 17, 2009 at 8:09 AM, Scott Webber <scottw@...> wrote:
> >
> >
> > I've been working w/ the same 2:1 epoxy
>
> Impossible to diagnose your problem from a distance, though...
>
> In my case when using 2:1 epoxy I found that about one batch in a
> hundred I would accidentally get things backwards and make the mix
> 1:2. The results were "rubbery mess".
>
> Since then I have switched to 1:1 epoxy and I am much happier with not
> needing to always be so vigilant with a touchy mix ratio. (I now
> usually get away with just 'eye-balling' half and half.)
>
Querstion did you thickern before or after mixing the epoxy and hardner. If fillers are added before they prevent it from mixing thoroughly befor adding fillers they mix poorly and unevenly. Putting in the freezer to slow or stop the reaction is a poor practice and only realy works for a limited time and makes it weeker. Most epoxies should not be heated over 180 deg. F to cure it also can weaken the epoxy. Double boiling keeps it at the boiling point of water to melt componets that crystalize in container. This is when they are not mixed so the reaction is not effected when it is cooled and remixed. Simply not steiring enough when mixing or some unmiked at the edges of mixing pot can also interfear with a good reaction. A little of conponets A or B left in a juge can alow some of the chemicals evaperate into the air space throwing off the chemistry. Fuller or full jugs will last longer if stored in a cooler place. I store mine in the laundry room with the pumps wraped up in a ziplock baggy. It stays normaly at about 65 deg. and the baggy catches any drips if the temp fluctuates very much. Do any of these things sound like they may be the posible problem.
Hope that helps. In humid areas for glassing and encapsolating try a Cycloaliphatic epoxy. It will not blush and humidity is not a problem with it. I have used a lot of it from this sorce and there are others.
http://www.jgreer.com/
Jon
Hope that helps. In humid areas for glassing and encapsolating try a Cycloaliphatic epoxy. It will not blush and humidity is not a problem with it. I have used a lot of it from this sorce and there are others.
http://www.jgreer.com/
Jon
--- Inbolger@yahoogroups.com, "gbship" <gbship@...> wrote:
>
> Sometimes epoxy is must mysterious. There's a local commercial fishing boat supplier that sells an inexpensive 4:1 and 5:1 epoxy. I've had the same problem, mostly with the 4:1 stuff, mixed carefully and thickened with wood flour. The stuff set rubbery, although it did, after a few weeks, eventually harden. Unthickened, it will usually set tack free in a day or so, but may take several days to harden enough to sand. But sometimes it's quicker setting than others. Like you, humidity is my guess as the variable (since I live in Florida), but it's just a guess.
>
> Gary
Sometimes epoxy is must mysterious. There's a local commercial fishing boat supplier that sells an inexpensive 4:1 and 5:1 epoxy. I've had the same problem, mostly with the 4:1 stuff, mixed carefully and thickened with wood flour. The stuff set rubbery, although it did, after a few weeks, eventually harden. Unthickened, it will usually set tack free in a day or so, but may take several days to harden enough to sand. But sometimes it's quicker setting than others. Like you, humidity is my guess as the variable (since I live in Florida), but it's just a guess.
Gary
Gary
--- Inbolger@yahoogroups.com, "titanicslim" <titanicslim@...> wrote:
>
> --- Inbolger@yahoogroups.com, "Scott Webber" <scottw@> wrote:
> >
> > I've been working w/ the same 2:1 epoxy laminating resin for years.
> > Always w/ success. A strange thing happened the other day. I made a
> > small quantity from a gallon kit that I'd used most of recently.
>
> Hi, Scott
>
> The thing that I focus on, because of past epoxy difficulties I have experienced, is the epoxy itself. I stopped using System 3 because of it.
>
> After a situation that sounds a lot like yours I was told by a chemist that the component parts of epoxy, if left to sit a long time, may separate in the bottle so that the mixture of the two parts will not give you the required mixture. In other words, I wonder if one of your "A" or "B" bottles might have stratified and left you with an incomplete or imbalanced composition and given you a less-than-optimal final mixture.
>
> The contaminated Cab-o-sil may or may not be complicating the issue but, if you suspect it, leave it out of your tests or get a fresh batch.
>
> Dave
>
--- Inbolger@yahoogroups.com, "Scott Webber" <scottw@...> wrote:
The thing that I focus on, because of past epoxy difficulties I have experienced, is the epoxy itself. I stopped using System 3 because of it.
After a situation that sounds a lot like yours I was told by a chemist that the component parts of epoxy, if left to sit a long time, may separate in the bottle so that the mixture of the two parts will not give you the required mixture. In other words, I wonder if one of your "A" or "B" bottles might have stratified and left you with an incomplete or imbalanced composition and given you a less-than-optimal final mixture.
The contaminated Cab-o-sil may or may not be complicating the issue but, if you suspect it, leave it out of your tests or get a fresh batch.
Dave
>Hi, Scott
> I've been working w/ the same 2:1 epoxy laminating resin for years.
> Always w/ success. A strange thing happened the other day. I made a
> small quantity from a gallon kit that I'd used most of recently.
The thing that I focus on, because of past epoxy difficulties I have experienced, is the epoxy itself. I stopped using System 3 because of it.
After a situation that sounds a lot like yours I was told by a chemist that the component parts of epoxy, if left to sit a long time, may separate in the bottle so that the mixture of the two parts will not give you the required mixture. In other words, I wonder if one of your "A" or "B" bottles might have stratified and left you with an incomplete or imbalanced composition and given you a less-than-optimal final mixture.
The contaminated Cab-o-sil may or may not be complicating the issue but, if you suspect it, leave it out of your tests or get a fresh batch.
Dave
On Fri, Apr 17, 2009 at 8:09 AM, Scott Webber <scottw@...> wrote:
In my case when using 2:1 epoxy I found that about one batch in a
hundred I would accidentally get things backwards and make the mix
1:2. The results were "rubbery mess".
Since then I have switched to 1:1 epoxy and I am much happier with not
needing to always be so vigilant with a touchy mix ratio. (I now
usually get away with just 'eye-balling' half and half.)
>Impossible to diagnose your problem from a distance, though...
>
> I've been working w/ the same 2:1 epoxy
In my case when using 2:1 epoxy I found that about one batch in a
hundred I would accidentally get things backwards and make the mix
1:2. The results were "rubbery mess".
Since then I have switched to 1:1 epoxy and I am much happier with not
needing to always be so vigilant with a touchy mix ratio. (I now
usually get away with just 'eye-balling' half and half.)
I've been working w/ the same 2:1 epoxy laminating resin for years.
Always w/ success. A strange thing happened the other day. I made a
small quantity from a gallon kit that I'd used most of recently. I
thickened w/ colloidal silica to mayo consistency and glued 2 pcs of
wood together. Like never before and at reasonably high temps (80 degF)
the mix cured to a stiff rubbery consistency after 24 hrs, not sticky,
but not hard as a rock either. I remember clearly that the mix
proportions and were correct and the mixing thorough.
Not to skew the answers but I left the top off the Cabosil for about a
week prior the glue up and it was quite humid. To test this premise I
heated some remaining from the mix (I had put some extra in the freezer
to see if it could be preserved and used later) in a water bath in the
microwave for a couple minutes to see if the water could be boiled off.
It got to the same hard rubbery consistency. That was followed by
heating in a toaster oven @ 200 degF for about 15 mins after which I
crumbled the rubbery mass between my fingers like a gum eraser.
Is it possible that the humidity dampened the Cabosil and caused this ?
What else could it be ?
Scott Webber
Always w/ success. A strange thing happened the other day. I made a
small quantity from a gallon kit that I'd used most of recently. I
thickened w/ colloidal silica to mayo consistency and glued 2 pcs of
wood together. Like never before and at reasonably high temps (80 degF)
the mix cured to a stiff rubbery consistency after 24 hrs, not sticky,
but not hard as a rock either. I remember clearly that the mix
proportions and were correct and the mixing thorough.
Not to skew the answers but I left the top off the Cabosil for about a
week prior the glue up and it was quite humid. To test this premise I
heated some remaining from the mix (I had put some extra in the freezer
to see if it could be preserved and used later) in a water bath in the
microwave for a couple minutes to see if the water could be boiled off.
It got to the same hard rubbery consistency. That was followed by
heating in a toaster oven @ 200 degF for about 15 mins after which I
crumbled the rubbery mass between my fingers like a gum eraser.
Is it possible that the humidity dampened the Cabosil and caused this ?
What else could it be ?
Scott Webber