Thinning Epoxy?

[sabahcat]

Originally Posted by tunnels

I was witness to some guys using uncatalysed resin to roll down some chopper gun overspray fibres half way through a hull lay up . I went off the deepend for even thinking of doing such a thing !! what about the secondry bond strength of the next laminate that goes on !, is it 100% or just 50% ??
If you work in a factory manufacturing enviroment and have 20 workers all watching each other and they start doing dumb things like that what would you do ??
Living by the seat of you pants you leaving to many things in you life to chance !,when dealing with any part of a boats manufacture you all ways do things 110% right never leave anything to chance because it will cost you or some one you love there life !!.
What works today may not work exactly the same next time .
If your boat comes apart at the seams 100 miles off shore in a rought sea its not only our life thats at risk its the souls that will hear you cryes for help and come to rescue you!!Simply because of not doing something properly .
So remeber as you walk towards those pearly gates in the sky ,watch for that slippery patch of uncatalysed resin you left on your path !!

WTF has any of that got to do with anything?

[tunnels]

Originally Posted by sabahcat

WTF has any of that got to do with anything?

Using un-catalyzed resin to prime wood with and then putting catalysed over the top !! Is what it has to do with !!
BAD PRACTICES !!

[sabahcat]

And what has that to do with correctly mixed epoxy with a small amount of thinning agent?
Tested repeatedly on boats that have sailed countless thousands of miles over decades

You are comparing apples with elephants

[michael pierzga]

And why would you thin epoxy when off the shelf you can purchase professionally formulated epoxy with different viscosities ?

[CC Guy]

Hi Guys I see we have some more thoughts on this, as we can see some manufactures will state there epoxy can be thinned to their spec, along with warming wood should help penetration which again is subject to the viscosity of the epoxy your starting with, the atmospheric condition, position your coating the wood in, type of wood will all play their part.

The blanket statement of NO thinning is too strong for a world view as it will depend on what you’re doing and what’s available in your part of the world.

My opinion would be do some simple test yourself before deciding what’s best for you.

As for my 75% test my aim is to stabilize wood movement not moisture protection which it has done compared to untreated test, which will prevent checking over a long time on a bright finish double planking boat.

I’m sure many are enjoying this discussion, my test is nothing new and would have already guest my aim.

[ancient kayaker]

Originally Posted by tunnels

I was witness to some guys using uncatalysed resin to roll down some chopper gun overspray fibres half way through a hull lay up . I went off the deepend for even thinking of doing such a thing !! what about the secondry bond strength of the next laminate that goes on !, is it 100% or just 50% ??
If you work in a factory manufacturing enviroment and have 20 workers all watching each other and they start doing dumb things like that what would you do ??

Sack 'em or train 'em! If you're not allowed to do the first and the second doesn't work then move the factory someplace else even if you have to pay higher labor rates.

Living by the seat of you pants you leaving to many things in you life to chance !,when dealing with any part of a boats manufacture you all ways do things 110% right never leave anything to chance because it will cost you or some one you love there life !!. What works today may not work exactly the same next time .
If your boat comes apart at the seams 100 miles off shore in a rought sea its not only our life thats at risk its the souls that will hear you cryes for help and come to rescue you!!Simply because of not doing something properly .

Totally agree!

So remeber as you walk towards those pearly gates in the sky ,watch for that slippery patch of uncatalysed resin you left on your path !!

Better watch out for your customers too!

[PAR]

It's purely mechanics folks, though on a very small level (actually not that small really).

To stabilize wood moment, you have to stop moisture vapor ingress/egress. This is the simple fact of it all, other wise wood will swell and contract. The only way to do this is to insure less then 3% moisture absorption and start with fairly dry stock. This is why marine epoxies are formulated the way they are, why all formulators recommend 12% moisture content stock and also why the polyesters and vinylesters don't get the job done (they resist at 85% - 87% and 87% - 92% on the 30 day absorption test respectively). If your coating, regardless of penetration amount (hell, it could hover over the surface, so long as it stops moisture), can't resist moisture vapor transmission, below the 3% threshold, then you'll have "gain" or "lose" depending on the current environmental changes. These are the simple physical facts of the testing and analysis preformed since WBP possibilities in WW II discoveries. This is well established and given that all, every single one of the formulators, hang onto these same baselines and moisture content thresholds, speaks volumes about the validity of their (and my) position on the subjects.

Of course, unless we've all gotten it wrong for the last half a century and you've discovered something special, in which case you'll need more then some garage testing. For example what was the flexural modulus of your thinned goo against your baseline? Assuming a typical 3:1 formulation baseline of a half a million PSI, how did your goo fair? Tensile strength/elongation/modulus? Compression strength? How about hardness (Shore D or Barcol, which ever you prefer)? Naturally, I'd have to ask about water absorption rates too . . .

[Frog4]

does this apply to vacuum bagged wood components as well?

[PAR]

Any wood that is to be dimensionally stabilized with a plastic coating, regardless of the method, needs to resist moisture vapor ingress/egress to less then 3%.

[sabahcat]

Originally Posted by PAR

Of course, unless we've all gotten it wrong for the last half a century and you've discovered something special, in which case you'll need more then some garage testing. For example what was the flexural modulus of your thinned goo against your baseline? Assuming a typical 3:1 formulation baseline of a half a million PSI, how did your goo fair? Tensile strength/elongation/modulus? Compression strength? How about hardness (Shore D or Barcol, which ever you prefer)? Naturally, I'd have to ask about water absorption rates too . . .

Maybe you missed the bit where I said that the thinned "goo" (20ml of biocide to the litre) was the first coat just to soak into the ply and still leaving the ply looking quite dry.
ALL other coats were unadulterated, taking care of any of your fears.

[sabahcat]

Originally Posted by michael pierzga

And why would you thin epoxy when off the shelf you can purchase professionally formulated epoxy with different viscosities ?

I buy my epoxy in 44 gallon drums and it is already a low viscosity resin.
I only need a few litres of the epoxy with biocide added to it for the first coat to ply that will be immersed (Tank Baffles and sides or in areas with no access.(the only timber in the build to get the treatment)
Secondary coatings of unadulterated epoxy to these components I would prefer to use the same "Brand" of resin and apply while green so as to eliminate sanding between coats.