Epoxy coating plywood question?

re peel ply, try
http://www.airtechintl.com

 

There are no solvent thinners in Silver Tip resin or hardeners. Speak what you know. There are viscosity modifiers, some can have an ammonia like smell in confined spaces, but it's vapor pressure is high, so it dissipates quickly if well ventilated.

 

The viscosity modifier which thins the epoxy (I'm calling that a thinner because that's what it does.., it thins silvertip down), is really potent and evaporates quickly, giving silvertip that unique sweet smell.

It is not an ammonia smell... it is a sweet smell in the resin side.

That stuff gives you a huge headache when you are doing aa large surface area or laminating in confined spaces.

All hand lamination on my boat was done with silvertip, so I am speaking to what I know. Hundreds of gallons of silvertip used, pretty familiar with the characteristics.

 

It's not "tinned" down, it's viscosity is lowered by decreasing the surface tension of the resin/hardener combination. Silver tip is the most common epoxy molecule in use, for the marine environment, a Bisphenol A formulation. What you might be noting is the enzyl, used in it's formulation (about 15%), which does have a sort of sweet smell. All other epoxy formulations have glycidyl ether (also about 15%), which has a smell too, but this is the ammonia smell I mentioned.

 

could be nonyl pehenol

 

It seems like it could be the nonyl phenol. What's the purpose of that stuff?


Whatever it is, it's an additive to Silvertip that is a strong, organic chemical smell, not too far removed from the smell of benzene. Evaporates out of the epoxy as it cures, so... my theory is it's a "thinner" in a way because it leaves the solution and is not present after curing.

Also, Silvertip is thinner than straight epoxy for better wet out.

There is definitely stuff in it that's not in other brands of epoxy or even in other system three epoxies.

 

nonyl is used to 1) get the mix ratios to whole numbers, 2) 'water down the epoxy' i.e. a cheap additive to lower cost/increase profit - 3) no doubt a few useful purposes too.

see epoxyproducts.com/nonyl4u.html

paul oman
progressive epoxy polymers

 

Nonylphenols are often used in a variety of things, commonly as an emulsifier or solubilizer (as Paul mentioned). It's presence (to the nose) depends on where it's attached to the phenol ring and particularly if "branched" in structure. It's also used as a heat stabilizer in some plastics (PVC is one). I don't know the precise propriety chemical composition of Silver Tip (I do know it way better than the average guy), but considering the presence of the enzyl groups, nonylphenol doesn't seem the likely cause of the smell. Lastly, and again, there is no "thinner" in Silver Tip. Nothing leaves the resin/hardener combination during the cure. Once the two molecules are mixed, a new molecule is formed, based on the recomposed/assembled elements of the resin/hardener molecules. It's not like paint, where you need a vehicle to "commute" resin/pigments/dies, etc., which then flashes off, nor is it a catalyst reaction (accelerated chemical reaction), which can release segments (part or whole) of the various molecules in play. This is likely well over the head of most, beside Paul and I.

 

Paul, this is actually quite interesting.

I very much enjoy learning and then to some extent understanding details & processes.

It's not something that is reasonably available to learn about because it's not usually discussed in much detail unless in a class type situation.

This is a field that I know very little about but I appreciate the detailed information presented.

The details are where the interesting things are.

Don't stop the discussion and information. I really appreciate the opportunity to learn about epoxy & different functional aspects of it.

Cheers, Allen

 

Okay, you, me and Paul are interested, but most find this sort of discussion pretty "dry" reading.

 

Actually, PAR, a very strong organic vapor present in the BPA side *does* leave silver tip before mixing, during mixing and more rapidly during cure as the temperature increases.

I'm certainly sure you and Paul aren't the only 2 people here with a basic working knowledge of organic chemistry involved in the BPA/aliphatic amine epoxy reaction.

This strong organic vapor is present only in silvertip. Not in system three general purpose, not in quickfair, not in Mas epoxy, not in Raka epoxy, not in hardware store epoxy.

And lo and behold, the silvertip is a lower viscosity than the others...and has strong organic vapor off gassing.

What part about those facts point to there not being a somewhat volatile additive in slilvertip? Most likely one that lowers the viscosity, then gets out of the way of polymerization...?

 

LOL Mostly I just meant that I hope you continue such 'dry reading' subjects as I enjoy learning about such minutia.

Unfortunately I don't have anything to contribute to such discussions. But I do enjoy the information.

Cheers, Allen

 

Snowbirder, so you're suggesting the SilverTip version from System Three isn't 100% solids? Don't you think West System would have sued by now, to make them rewrite their advertising literature (at the very least), if this was the case?

My experience shows that several of the more common A formulations can have a initially strong smell, which most associate with being ammonia like. All of FGCI's base resins have this attribute, for example. The smell is from the molecular pressure of the amine groups and dissipates rapidly (very low vapor pressure), though dead air spaces can trap it for a while (like inside a can or jug). The faster the cure rate of the hardener, the more likely this will be the case (I've noticed). Nothing is evaporating, flashing off or other wise "leaving" the goo (hardener), it's just the physical construction of the polyamines (there are many) and some are more aromatic than others.

 

my Basic No Blush epoxy as a bit of a 'haze' and a bit of smell in the part A resin due to bubble breakers added to the resin - perhaps the only marine epoxy with bubble breakers - but does at a bit of a smell. - all this brngs home the differenced between epoxy formulators and epoxy repackagers...

paul
progressive epoxy polymers

 

I haven't used System Three before but have coated a great deal of okume with epoxy.

Don't apply the first coat too thick. I either rub it in with a brush, or spread sparingly with a roller. Pouring a puddle and spreading it with a knife is fast on large surfaces but I find it a little wasteful and its hard to meter everything out evenly. Okume soaks it up really fast.

Never had a problem with air bubbles. The first coat will be pretty much absorbed in the grain. On subsequent coats avoid using force when applying the epoxy. Gentle technique won't agitate the stuff so air won't get incorporated.

All products are different so I would suggest doing a small test piece. This will help identify any problems before you get started.