Boy this thread is getting a bit nasty. Calm down guys!

One more point I want to make that might help cool things down a bit.....

wood expands and contracts with moisture

things like epoxy, fiberglass, paint, and just about all other things,
expand and contract with temperature.
So - wood and the epoxy on it don't expand and contract together...
This can cause some of the issues brought up here. Always best to
complete seal the wood with epoxy, not just one side. Also, plywood,
because of the way it is made etc. expands and contracts very little (at
least compared to 'regular' wood).


Also epoxies stick really well to most materials and is often considered
sort of a universal primer.

polyester resin (fiberglass resin) doesn't bond well (or long) to
anything but itself (I and my customers report polyester resin to wood
bond failures after a few years maybe 10 years at best). This is why
fiberglass boats are generally 100% fiberglass and not half fiberglass
and half wood (as might/could be the case with epoxy resin). So.... you
can repair fiberglass with epoxy but fixing epoxy with fiberglass resin
in not recommend (but many folks do and they get away with it).

Epoxy resins just have all around better physical properties than
polyester resin, but usually cost more.

I vaguely recall seeing water absorption numbers for epoxy at something
like 1/10 of a percent. Don't ask me where or how I got that number,
just something that is floating adrift in my head.


cheers everyone

paul oman
progressive epoxy polymers






Lodewijk Stegman wrote:

schreef in
oups.com



On Jul 11, 4:21 pm, Lodewijk Stegman
wrote:





I'm sorry to say, but you ARE wrong. It is almost impossible to use
epoxy and wood together without depending on the waterproof qualities
of epoxy. I wonder what you have used it for and how you engineer
your work if you're so sure it leaks.



Have a great day and go build a boat!


Sure. You go build a heavy wooden boat. But don't use epoxy. You're
not knowledgeable enough.





You don't know what you don't know. You certainly know nothing about
me and my experience. Next time however it would help if your read my
post and Pauls (epoxy expert, retailer) post for content, instead of
just trying to feed your ego with ignorant insults. Later kid...



There's not all that much content in your post.

Maybe you should point out your experiences and your engineering.
I meant what I said when I stated that it's almost impossible to use wood
and epoxy together if you don't rely on it's waterproof qualities.

For instance: wood shrinks and swells with changing humidity. Epoxy won't
move with it. How do you engineer that?

On Thu, 12 Jul 2007 03:13:56 GMT, Paul Oman
wrote:


Boy this thread is getting a bit nasty. Calm down guys!

One more point I want to make that might help cool things down a bit.....

wood expands and contracts with moisture

things like epoxy, fiberglass, paint, and just about all other things,
expand and contract with temperature.
So - wood and the epoxy on it don't expand and contract together...
This can cause some of the issues brought up here. Always best to
complete seal the wood with epoxy, not just one side. Also, plywood,
because of the way it is made etc. expands and contracts very little (at
least compared to 'regular' wood).


Also epoxies stick really well to most materials and is often considered
sort of a universal primer.

polyester resin (fiberglass resin) doesn't bond well (or long) to
anything but itself (I and my customers report polyester resin to wood
bond failures after a few years maybe 10 years at best). This is why
fiberglass boats are generally 100% fiberglass and not half fiberglass
and half wood (as might/could be the case with epoxy resin). So.... you
can repair fiberglass with epoxy but fixing epoxy with fiberglass resin
in not recommend (but many folks do and they get away with it).

Epoxy resins just have all around better physical properties than
polyester resin, but usually cost more.

I vaguely recall seeing water absorption numbers for epoxy at something
like 1/10 of a percent. Don't ask me where or how I got that number,
just something that is floating adrift in my head.


cheers everyone

paul oman
progressive epoxy polymers


Ha! Maybe a chance to get me some free information here =;-}

If you were planning on building a composite potable water tank what
would you use to line/paint the inside?

I have had several boats that had integral tanks. In one case the tank
appeared to have been painted inside with polyester resin and a second
boat that appeared to have gel coat on the inside.

I am considering building a spare water tank out of plywood, lined and
taped with glass, and do not have a big selection of epoxy available
here. My thoughts were to go ahead and paint it inside with several
coats of epoxy, let it cure for several weeks and then flush it with
several/many changes of water.

If some form of special, "This stuff is for lining water tanks" resin
was available I'd use it but as far as I can discover there is
nothing like that available in the country.

Thanks for any information you can give me.





Bruce in Bangkok
(brucepaigeatgmaildotcom)

--
Posted via a free Usenet account from http://www.teranews.com

Ha! Maybe a chance to get me some free information here =;-}

If you were planning on building a composite potable water tank what
would you use to line/paint the inside?

I have had several boats that had integral tanks. In one case the tank
appeared to have been painted inside with polyester resin and a second
boat that appeared to have gel coat on the inside.

I am considering building a spare water tank out of plywood, lined and
taped with glass, and do not have a big selection of epoxy available
here. My thoughts were to go ahead and paint it inside with several
coats of epoxy, let it cure for several weeks and then flush it with
several/many changes of water.

If some form of special, "This stuff is for lining water tanks" resin
was available I'd use it but as far as I can discover there is
nothing like that available in the country.

Thanks for any information you can give me.





Bruce in Bangkok
(brucepaigeatgmaildotcom)



---------------

gel coat is just thickened polyester resin.

epoxies tested and approved for potable water (NSF 61 approvals) are
generally (always????) test /approved for tanks over 1000 gallons or
pipelines over 16 inches dia. Some folks don't worry about it, others
do......

paul
- progressive epoxy polymers

On Thu, 12 Jul 2007 12:19:56 GMT, Paul Oman
wrote:


Ha! Maybe a chance to get me some free information here =;-}

If you were planning on building a composite potable water tank what
would you use to line/paint the inside?

I have had several boats that had integral tanks. In one case the tank
appeared to have been painted inside with polyester resin and a second
boat that appeared to have gel coat on the inside.

I am considering building a spare water tank out of plywood, lined and
taped with glass, and do not have a big selection of epoxy available
here. My thoughts were to go ahead and paint it inside with several
coats of epoxy, let it cure for several weeks and then flush it with
several/many changes of water.

If some form of special, "This stuff is for lining water tanks" resin
was available I'd use it but as far as I can discover there is
nothing like that available in the country.

Thanks for any information you can give me.





Bruce in Bangkok
(brucepaigeatgmaildotcom)



---------------

gel coat is just thickened polyester resin.

epoxies tested and approved for potable water (NSF 61 approvals) are
generally (always????) test /approved for tanks over 1000 gallons or
pipelines over 16 inches dia. Some folks don't worry about it, others
do......

paul
- progressive epoxy polymers

Thanks, I understand.


Bruce in Bangkok
(brucepaigeatgmaildotcom)

--
Posted via a free Usenet account from http://www.teranews.com

On Jul 11, 11:13 pm, Paul Oman wrote:
Boy this thread is getting a bit nasty. Calm down guys!

One more point I want to make that might help cool things down a bit.....

Sorry, I am a nasty guy and I don't like being slandered by some punk
kid.

I vaguely recall seeing water absorption numbers for epoxy at something
like 1/10 of a percent. Don't ask me where or how I got that number,
just something that is floating adrift in my head.

And that was my simple point. Even in a lab epoxy is not "waterproof",
I know it sounds picky with the numbers you stated, but who uses epoxy
in lab conditions anyway. And certainly in the use the Origional
Poster has in mind it won't be water proof, in fact it may prove
detremental by holding aquired moisture (through cracks and osmosis)
in. Even if he went to the expence of using the water tank rated stuff
you base your numbers on, and certainly not if he uses off the shelf
maring epoxy...


cheers everyone

Cheers to you too, but the guy owes me an apology.


paul oman
progressive epoxy polymers

On Jul 12, 10:33 am, wrote:


Cheers to you too, but the guy owes me an apology.

Better yet, just let it die, my feelings will heal