# [EVDL] Fiberglass problem



## EVDL List (Jul 27, 2007)

Okay, this past Saturday I started to work with the Epoxy resin for 
fiberglassing my battery boxes.
Since the boxes are plywood construction, the instructions said to just 
apply epoxy to the wood first and let it dry.
Of course, that day was about 55 def F, right at the bottom of the 
allowable temps.
And it's been running colder since then.
On Sunday afternoon, I noticed that the epoxied plywood was still very 
sticky.
So I stuck a 1000W electric heater blowing up into the upside down box.
Today, tuesday, it's still rather sticky.

Is there any hope for getting this stuff to dry properly?

-- 
--
John G. Lussmyer mailto:[email protected]
Electric Vehicle Battery Monitoring Systems, http://www.CasaDelGato.com


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## EVDL List (Jul 27, 2007)

John,

Mixing up epoxy needs to be done within the temp range according to 
your instructions. There is a chance it will not work. Give it more 
time with that extra warmth and if you can cover the vehicle so the 
whole mess is kept warm (not hot) it may stiffen up. I'd only do epoxy 
work when the weather is warm and minimal humidity. I always got my 
ply wet then laid on the first layer of glass and then slowly added 
the required glass layers as I went along. I even went back the next 
day but before the first 24 hours and laid on a few more layers. Make 
sure you get the air out. Don't be in too big of a hurry but not too 
slow either. Practice on samples firs if you are not sure of your mix. 
I always had good luck.

Pete : )





> John G. Lussmyer wrote:
> 
> > Okay, this past Saturday I started to work with the Epoxy resin for
> > fiberglassing my battery boxes.
> ...


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## EVDL List (Jul 27, 2007)

Working at the bottom of the temperature range and below is a no-no. It 
does not matter how much catalyst that is added to generate a chemical 
reaction, it will not kick. You will need to wait for a day that is 
definitely within the mid safe curing range. Try testing a small area with 
a hotter mix (more catalyst) than usual in order to get the original epoxy 
to kick. If no success, then you may have to clean out as much as possible 
with acetone and wait for warmer weather. Wear gloves and in good 
ventilation with all chemicals. Good luck.

----- Original Message ----- 
From: "John G. Lussmyer" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Tuesday, April 14, 2009 10:23 PM
Subject: [EVDL] Fiberglass problem


> Okay, this past Saturday I started to work with the Epoxy resin for
> fiberglassing my battery boxes.
> Since the boxes are plywood construction, the instructions said to just
> apply epoxy to the wood first and let it dry.
> Of course, that day was about 55 def F, right at the bottom of the
> allowable temps.
> And it's been running colder since then.
> On Sunday afternoon, I noticed that the epoxied plywood was still very
> sticky.
> So I stuck a 1000W electric heater blowing up into the upside down box.
> Today, tuesday, it's still rather sticky.
>
> Is there any hope for getting this stuff to dry properly?
>
> -- 
> --
> John G. Lussmyer mailto:[email protected]
> Electric Vehicle Battery Monitoring Systems, http://www.CasaDelGato.com
>
>
> _______________________________________________
> General EVDL support: http://evdl.org/help/
> Usage guidelines: http://evdl.org/help/index.html#conv
> Archives: http://evdl.org/archive/
> Subscription options: http://lists.sjsu.edu/mailman/listinfo/ev
> 

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## EVDL List (Jul 27, 2007)

This is not correct. You cannot change the mix ratio with epoxy the way you
can with polyester resin. Epoxy is a two part cross linked product, not
catalyzed, and too little or too much hardener will leave you with unlinked
molecules, in other words, goop. Many products have different speed
hardeners for different working times and temperatures. 
John



> Steve Adams-9 wrote:
> >
> > Working at the bottom of the temperature range and below is a no-no. It
> > does not matter how much catalyst that is added to generate a chemical
> ...


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## EVDL List (Jul 27, 2007)

Yes, I agree with John. But all is not lost. I have had similar 
results when working at low temperature. It eventually does cure. It 
is a bit concerning that when you add heat it gets even more tacky. 
I have had this happen as well. Give it a week and hope for better 
working weather. It will eventually harden if you mixed it properly.




> AMPhibian wrote:
> 
> >
> > This is not correct. You cannot change the mix ratio with epoxy the
> ...


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## EVDL List (Jul 27, 2007)

I've been there too, and it did become not-sticky after some weeks but I always wondered if the strength had been compromised - does anyone know? 

My project was a foam-core covered with fiberglass mat and polyester resin (like a surf board, it was actually a Doran). 

-Chris




________________________________
From: Roger Heuckeroth <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Wednesday, April 15, 2009 8:26:10 AM
Subject: Re: [EVDL] Fiberglass problem

Yes, I agree with John. But all is not lost. I have had similar 
results when working at low temperature. It eventually does cure. It 
is a bit concerning that when you add heat it gets even more tacky. 
I have had this happen as well. Give it a week and hope for better 
working weather. It will eventually harden if you mixed it properly.




> AMPhibian wrote:
> 
> >
> > This is not correct. You cannot change the mix ratio with epoxy the
> ...


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## EVDL List (Jul 27, 2007)

> Christopher Darilek wrote:
> 
> > My project was a foam-core covered with fiberglass mat and
> > polyester resin (like a surf board, it was actually a Doran).
> ...


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## EVDL List (Jul 27, 2007)

I did not finish it. 
I sold it to a man who had helped me with it and who did finish it, EV.
It's a great looking car - especially if you have the fiberglassing skills...
-Chris




________________________________
From: Doug Weathers <[email protected]>
To: Electric Vehicle Discussion List <[email protected]>
Sent: Wednesday, April 15, 2009 3:18:08 PM
Subject: Re: [EVDL] Fiberglass problem




> Christopher Darilek wrote:
> 
> > My project was a foam-core covered with fiberglass mat and
> > polyester resin (like a surf board, it was actually a Doran).
> ...


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## EVDL List (Jul 27, 2007)

> John G. Lussmyer wrote:
> > Okay, this past Saturday I started to work with the Epoxy resin for
> > fiberglassing my battery boxes.
> > Since the boxes are plywood construction, the instructions said to just
> ...


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## EVDL List (Jul 27, 2007)

There should not be any wax in epoxy. There is something called "amine
blush" which forms on the surface of fully cured epoxy and is clear, but if
what he has is still sticky then it's not cured yet.
John



> Cory Cross-2 wrote:
> >
> > John G. Lussmyer wrote:
> >> Okay, this past Saturday I started to work with the Epoxy resin for
> ...


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## EVDL List (Jul 27, 2007)

> AMPhibian wrote:
> > There should not be any wax in epoxy. There is something called "amine
> > blush" which forms on the surface of fully cured epoxy and is clear,
> Sorry, amine blush is "waxy", not wax. On the epoxy I've used, I'm 90%
> ...


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## EVDL List (Jul 27, 2007)

> Cory Cross wrote:
> > Right, but I was saying if he wants to add more of a properly mixed
> > batch overtop, he sure wash off any existing amine blush (if it's
> > partially-cured, there will be some). However, the experts disagree with
> ...


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## EVDL List (Jul 27, 2007)

Here's a hint for dealing with large-ish amounts of epoxy. The curing
reaction is exothermic so if you mix/hold it in a pail, it traps the
heat which makes it cure all the faster resulting in a runaway reaction.
Instead, put it in something low and flat--spread it out so the heat can
dissipate. That extends the pot life quite a bit. But, yes, 2 qts is a
lot to spread all at once if you're new to this.

--Steve



> John G. Lussmyer wrote:
> > Cory Cross wrote:
> > > Right, but I was saying if he wants to add more of a properly mixed
> > > batch overtop, he sure wash off any existing amine blush (if it's
> ...


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## EVDL List (Jul 27, 2007)

John,

I used West Epoxy for my old boat and know about that heat. It melted 
my stir stick and that was just a small cup of stuff mixed up. If you 
are getting your mix to set too fast then you need a different 
hardener to slow the process. They do sell different hardeners so you 
can better taylor your mix for the temp and humidity you happen to be 
working in. There is fast medium and slow and they do work. I have 
fast and medium speed hardener. Works like a charm. For sure use less 
per batch unless you have a couple folks to help spread it out so you 
can do it real fast and take the advice of putting it in a low flat 
pan to help keep it longer. It does work. West Epoxy recommends that 
technique.


Pete : )





> John G. Lussmyer wrote:
> 
> > Cory Cross wrote:
> >> Right, but I was saying if he wants to add more of a properly mixed
> ...


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## EVDL List (Jul 27, 2007)

Just an idea, never tried it myself.

What about mixing in a cup, then put it in an ice bucket to cool the mix while you work? 

Stub
Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: [email protected]

Date: Fri, 1 May 2009 07:04:53 
To: Electric Vehicle Discussion List<[email protected]>
Subject: Re: [EVDL] Fiberglass problem


John,

I used West Epoxy for my old boat and know about that heat. It melted 
my stir stick and that was just a small cup of stuff mixed up. If you 
are getting your mix to set too fast then you need a different 
hardener to slow the process. They do sell different hardeners so you 
can better taylor your mix for the temp and humidity you happen to be 
working in. There is fast medium and slow and they do work. I have 
fast and medium speed hardener. Works like a charm. For sure use less 
per batch unless you have a couple folks to help spread it out so you 
can do it real fast and take the advice of putting it in a low flat 
pan to help keep it longer. It does work. West Epoxy recommends that 
technique.


Pete : )





> John G. Lussmyer wrote:
> 
> > Cory Cross wrote:
> >> Right, but I was saying if he wants to add more of a properly mixed
> ...


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## EVDL List (Jul 27, 2007)

On Fri, 2009-05-01 at 14:22 +0000, [email protected] wrote:
> Just an idea, never tried it myself.
> 
> What about mixing in a cup, then put it in an ice bucket to cool the mix while you work? 
> 

That'd make it too viscous to spread. Normally you want the stuff
between 70-80F while applying it, then crank up the heat to cure.

--Steve

> 
> -----Original Message-----
> From: [email protected]
> 
> Date: Fri, 1 May 2009 07:04:53 
> To: Electric Vehicle Discussion List<[email protected]>
> Subject: Re: [EVDL] Fiberglass problem
> 
> 
> John,
> 
> I used West Epoxy for my old boat and know about that heat. It melted 
> my stir stick and that was just a small cup of stuff mixed up. If you 
> are getting your mix to set too fast then you need a different 
> hardener to slow the process. They do sell different hardeners so you 
> can better taylor your mix for the temp and humidity you happen to be 
> working in. There is fast medium and slow and they do work. I have 
> fast and medium speed hardener. Works like a charm. For sure use less 
> per batch unless you have a couple folks to help spread it out so you 
> can do it real fast and take the advice of putting it in a low flat 
> pan to help keep it longer. It does work. West Epoxy recommends that 
> technique.
> 
> 
> Pete : )
> 


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## EVDL List (Jul 27, 2007)

> Dave King wrote:
> > 2 quarts of epoxy is way too much in one mix. Probably about 1/4 of that is
> > what you should work with and even that depends on the day ie temps.
> >
> ...


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## EVDL List (Jul 27, 2007)

Sure does. Remember how your big, thick pot of epoxy got hot and smoked? 
Thicker means more heat, which means more chemical activity, which means
faster cross linking. Remember, it's not like paint, it doesn't dry, it
cures.

John




> John G. Lussmyer wrote:
> >
> >
> >
> ...


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## EVDL List (Jul 27, 2007)

> Dave King wrote:
> > If you mixed that bad layup epoxy properly then eventually it can but
> > necessarily will
> > cure up. If you can heat it up and keep it warm for a day it might
> ...


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## EVDL List (Jul 27, 2007)

John -
If your shop is at 60F, you shouldn't need heaters at all.

If you're sure you're mixing it in the right ratio ( and are stirring it
enough) the epoxy is at fault. Just chuck it. Even if it eventually cures,
you'll never know if it end up as strong ( or adheres as well to the
substrate) as it should .

Try a different batch ( and brand). I like MAS brand (with the slow-cure
hardener), I've been using it - mostly for boats, but also for battery
boxes - for about 15 years. It's easy to use, relatively cheap, and has a
long working time. It also has no amine blush. It will cure ( if slowly - a
few days) down to 40F.


I've only had it fail to cure once - when I mistakenly mixed it 1 : 1 (
it's supposed to be 2:1)

Phil



> John G. Lussmyer <[email protected]>wrote:
> 
> > Dave King wrote:
> > > If you mixed that bad layup epoxy properly then eventually it can but
> ...


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## EVDL List (Jul 27, 2007)

All this talk about fiberglass makes me wonder -
is it possible to build a battery box by framing
in with flat iron and then setting in a mold of some sort?

(I'm imagining it a little like concrete mold,
but not sure that's a good model ;-)

Or does fiberglass need the surface area of something
like plywood?


(note, I'm not sure about this whole idea
"I need to learn to weld to make an EV.
I need to learn to troubleshoot a welder
to learn to weld..."
I bought a used welder and loaned it out,
and it came back with a bad report "doesn't work".

(It's OK, a good friend of mine is an experienced
welder and ECE, is looking at it. Asking for lessons ;-)

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## EVDL List (Jul 27, 2007)

What kind of welder. A few hours practicing with a wire feed and you can
make decent welds. Stick I'm still not very good at, and I've never tried
TIG or gas welding.

Z



> Seth Rothenberg <[email protected]>wrote:
> 
> >
> >
> ...


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## EVDL List (Jul 27, 2007)

> Phil Marino wrote:
> > John -
> > If your shop is at 60F, you shouldn't need heaters at all.
> >
> ...


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## EVDL List (Jul 27, 2007)

> Seth Rothenberg wrote:
> > is it possible to build a battery box by framing in with flat iron
> > and then setting in a mold of some sort? (I'm imagining it a little
> > like concrete mold, but not sure that's a good model ;-)
> ...


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## EVDL List (Jul 27, 2007)

Here is another way I did it with my fiberglass battery boxes.

I was going to make a plywood box mode and glue on vinyl floor covering for 
a smooth inside surface. The Custom Fiberglass Company said, I would have 
to make the sides taper a little, or you may not get it out.

So I opt for laying down a sheet of of 4 feet by 8 feet smooth sheet metal 
on a 4 feet by 8 feet by 3/4 inch plywood which is support by four saw 
horses.

Now I made a 6 feet by 42 inch bottom piece of the battery box by clamping 
steel 1/4 x 1/4 inch angle iron to form a the 6 feet by 42 inch section on 
the sheet metal. The side angle irons control the height of the laying up 
of the fiberglass.

I first brush on a mode release on the sheet metal, or you could use a floor 
wax. I then precut all the fiberglass cloth to size. I use four layers of 
cloth to make 1/4 inch thick sections. The lay up pattern is to lay the 
finish weave down on the surface of the metal and work up with heaver weave.

I mix about a 1/4 gallon of resin and the tube of harder at a time. For the 
6 feet by 42 inch by 1/4 inch section which is 758 cu.in. and it takes about 
216 cu.in. per gallon. I pour the whole works at one time and then quickly 
lay up all the layers of cloth on the resin. Use a smooth paint roller or a 
wall paper rubber roller to press the cloth into the resin.

Use a straight edge across the form resting on the angle iron and pull it 
across the form while tamping it. Just like they do when they finish 
concrete.

The top side of the fiberglass sheet will be some what rough, but the inside 
will be very smooth. After it cures, just release the side angle supports.

I also made 2 by 2 inch fiberglass angles for making a flange on the top 
edge of the fiber glass box. Also made 4 by 4 inch fiberglass angles that 
are lay up on the outside bottom joints with extended out for bolting to the 
a support.

To make these angle pieces, just use a length of angle iron for a form.

All these sections are fiberglass together at all the joints on the outside 
of the box only using several layers of medium weight cloth which each cloth 
overlaps it sections by 2 inches and built up to 1/4 inch thick.

Do not butt the fiberglass sheets together at the joint. Leave about a 1/8 
inch gap in all areas. After the box is cure, then apply fiberglass putty 
into the inside joints. To smooth these joints, I clamp a aluminum angle 
into the joints which makes it very smooth.

I coated the inside of the fiberglass box with one of those Sink and Tub 
refinishing kits that I got from Home Depot. This stuff is thick, so I thin 
it out with epoxy thinner. I apply it to each section while it was that 
section was lay flat by turning the box sections.

I then glue on 2 inch thick polystyrene Dow Blue foam which is good to 25 
lbs per sq in on the outside of the box. Use foam glue only, other glue will 
melt the foam. I then glue on a marine carpet over the foam so as to 
protect it when I slid it into my pickup bed which was also cover with this 
foam and marine carpet. This also gave me over 20 R-factor.

Roland




----- Original Message ----- 
From: "Lee Hart" <[email protected]>
To: "Electric Vehicle Discussion List" <[email protected]>
Sent: Saturday, May 09, 2009 3:25 PM
Subject: Re: [EVDL] Fiberglass problem




> > Seth Rothenberg wrote:
> > > is it possible to build a battery box by framing in with flat iron
> > > and then setting in a mold of some sort? (I'm imagining it a little
> > > like concrete mold, but not sure that's a good model ;-)
> ...


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