Treated plywood

[jigngrub]

Re: Treated plywood

While epoxy works far better for sealing wood when no glass is used and has little to no odor, it can be highly toxic, far more than a polyester. So saying it's safer can be misleading.

Some epoxies can be highly toxic, like the CPES... others like the 635 thin epoxy from USComposites, not so much.

I'd say the worst epoxies and poly resin are about the same when you factor in all of the dangers, do some MSDS research for each and you'll see what I'm talking about.

 

[ondarvr]

Re: Treated plywood

I supply the MSDS's to the end users, so I know them well. I have also worked with both types of resin for decades, polyesters show little to no health issues in the workforce and makes up 95% of the market. Epoxy use is far less frequent but I know many people that have been sensitized to it and can no longer be around it. Yes there are safer types and formulas, but for the average person it would be difficult to know which one you are using.

I have come in contact with literally thousands of workers in glass shops, while not pleasant at times, polyesters tend to be on the safer side when compared to epoxies.

 

[jigngrub]

Re: Treated plywood

I supply the MSDS's to the end users, so I know them well.

Hey! That's great, maybe you can post a link to MSDS for a couple of the more popular brands so the average person can see just what they're working with. Polyester and epoxy resins, if it's not too much trouble and since you know them well.

Maybe we can get a MSDS sticky going in the "How-to" forum/thread so the average back yard boat builder can stay safe?

 

[Mud Puppy]

Re: Treated plywood

The epoxies we use are pretty safe to work with and all two part epoxies including thixotropic epoxies used in aviation become benign after cured, it is when they are separate chemicals they are not so much. During the mixing and catalytic stages is when all are something to be aware of when handling/ breathing.

The new floor in my boat was sealed using one layer of 15oz harness weave and laid down with a two part aviation epoxy. IT was never painted or gelcoated and became very brittle and allowed water intrusion which didn't mater much as there were other issues at the transom, thus I am tearing mine out to the hull.

I would personally take a thick coat of poly and multiple layers of CSM with a layer of 1708 for the wear aspects over epoxy and one layer of glass.

Like anything else, no matter what is used, it boils down to prep, materials, finish, and maintenance. I don't think any product ever designed is completely maintenance free.

 

[jigngrub]

Re: Treated plywood

The new floor in my boat was sealed using one layer of 15oz harness weave and laid down with a two part aviation epoxy. IT was never painted or gelcoated and became very brittle and allowed water intrusion which didn't mater much as there were other issues at the transom, thus I am tearing mine out to the hull.

If that epoxy was never covered to protect it from UV breakdown you can't expect any thing other than what happened to it.

 

[ondarvr]

Re: Treated plywood

Here is a typical polyester resin MSDS and ones for West System resin and hardener, it's normally the epoxy hardener that causes problems.

On the polyester MSDS note what it says about actual long term health studies. It is well known that you can become sensitized to epoxies and from that time on even contact with the grinding dust can cause reactions.


http://host1.ccponline.com/msds/pdf/LSPA2200.pdf

http://www.westsystem.com/ss/assets/MSDS/MSDS205.pdf

http://www.westsystem.com/ss/assets/MSDS/MSDS105-404.pdf

 

[ondarvr]

Re: Treated plywood

The epoxies we use are pretty safe to work with and all two part epoxies including thixotropic epoxies used in aviation become benign after cured, it is when they are separate chemicals they are not so much. During the mixing and catalytic stages is when all are something to be aware of when handling/ breathing.

The new floor in my boat was sealed using one layer of 15oz harness weave and laid down with a two part aviation epoxy. IT was never painted or gelcoated and became very brittle and allowed water intrusion which didn't mater much as there were other issues at the transom, thus I am tearing mine out to the hull.

Other than the silica or other items used to thicken the epoxy it is exactly the same as its unthickend counter part. Yes,when fully cured it rarely causes problems, but unless it's been post cured it can take very long time for it to fully cure, from days to weeks, maybe even longer in cool climates. Until then it can still cause allergic reactions.


Like jigngrub said, unless the epoxy is protected from UV rays it can break down and fail.

 

[Mud Puppy]

Re: Treated plywood

Like jigngrub said, unless the epoxy is protected from UV rays it can break down and fail.

Even painted or gelcoated I just can't see it being as durable as the poly due to thickness.

Most of what we use is prepreg and requires hours at or above the service temperature of the adhesive system for postcure. The ambient temperature stuff is good, just not qualified as high for tensile, modulus, and environment strengths, the same would be true for boat epoxy.

We all have different experiences, some good, some not so good. I just know you can't do something halfway and expect it to last forever! :grouphug:

I think we need to get back on track with the original thread however as we have covered most of what it was originally about and then some. :bump2:


hadaveha, I wouldn't use anything without sealing it and I wouldn't recommend treated anytime. I think you are on the right track however.

Let us know how you do!

 

[ondarvr]

Re: Treated plywood

The thickness is determined by the end use, not enough glass in either product will result in failure on a surface that will receive heavy traffic or abuse. It appears more glass and paint are what was needed for your application. If both are used at the same thickness the epoxy product would be tougher.

"The ambient temperature stuff is good, just not qualified as high for tensile, modulus, and environment strengths, the same would be true for boat epoxy."

I like that you mentioned that, most people don't know that the physical properties of epoxies are tested after being post cured. Without being post cured they don't come close to as strong as what the spec sheet says.


"hadaveha, I wouldn't use anything without sealing it and I wouldn't recommend treated anytime. I think you are on the right track however."

Why would you recommend against it?

 

[jigngrub]

Re: Treated plywood

Here is a typical polyester resin MSDS and ones for West System resin and hardener, it's normally the epoxy hardener that causes problems.

On the polyester MSDS note what it says about actual long term health studies. It is well known that you can become sensitized to epoxies and from that time on even contact with the grinding dust can cause reactions.


http://host1.ccponline.com/msds/pdf/LSPA2200.pdf

http://www.westsystem.com/ss/assets/MSDS/MSDS205.pdf

http://www.westsystem.com/ss/assets/MSDS/MSDS105-404.pdf

You forgot the MSDS for the MEKP:

MSDS for MEK-P Methyl Ethyl Ketone Peroxide Catalyst / Hardener for Polyester Resin


Anyone that takes the time to compare the 2 polyester resin components to the 2 epoxy will see quite a difference in volatility and health hazards with epoxy being the far lesser of the evils.


I've noticed a lot of the fiberglass guys want to downplay the hazards of polyester resin here and I don't really understand it, maybe it's like the Japanese people and the Fugu fish?

 

[zool]

Re: Treated plywood

Anyone that takes the time to compare the 2 polyester resin components to the 2 epoxy will see quite a difference in volatility and health hazards with epoxy being the far lesser of the evils.


I've noticed a lot of the fiberglass guys want to downplay the hazards of polyester resin here and I don't really understand it, maybe it's like the Japanese people and the Fugu fish?

One thing I can say is ive become sensitized to epoxy during this build...it started out as just split finger tips, but by now, if im not real careful during a session, both my hands get covered in rash that lasts a week....it dies down when away from it, but hasn't completely redacted...I may be forced to use poly on my next build.

 

[Mud Puppy]

Re: Treated plywood

Why would you recommend against it?

Closed cell and moisture content mostly. Check post #11. I also wouldn't use it in or around aluminum period!

Anyone that takes the time to compare the 2 polyester resin components to the 2 epoxy will see quite a difference in volatility and health hazards with epoxy being the far lesser of the evils.

I've noticed a lot of the fiberglass guys want to downplay the hazards of polyester resin here and I don't really understand it,~

Neither are as safe as mother's milk that is for sure, but using the correct PPG, it shouldn't be an issue with either unless someone is gonna try and cowboy it in with bare hands and chew it like dip.

 

[Woodonglass]

Re: Treated plywood

I know I read on hear somewhere to not use pressure treated plywood in your aluminum boat, I was just wondering why, I have helped replace the floor in a lowes bass boat, and a pontoon boat, both came from the factory with pressure treated plywood, does it do something to aluminum

I REALLY think the OP deserves his thread to be used to discuss the pros and cons of PT plywood. That WAS his topic of interest if I'm not mistaken. I believe it has been covered but I may be wrong. I have been before!!!

 

[ondarvr]

Re: Treated plywood

You forgot the MSDS for the MEKP:

MSDS for MEK-P Methyl Ethyl Ketone Peroxide Catalyst / Hardener for Polyester Resin


Anyone that takes the time to compare the 2 polyester resin components to the 2 epoxy will see quite a difference in volatility and health hazards with epoxy being the far lesser of the evils.


I've noticed a lot of the fiberglass guys want to downplay the hazards of polyester resin here and I don't really understand it, maybe it's like the Japanese people and the Fugu fish?

They don't get downplayed, you just need to be real about it. The studies show few, if any, long term issues with polyester, only suspected possible issues. With epoxy there are real health concerns that have affected many people even though far fewer people use it. Remember, my life is composites, I've been in the kitchen for decades using it first hand. My experience is not from reading about it online, or a couple of hobby projects. MEKP has potential problems if you get it in your eyes, most people don't come in contact with it like they would the resins though. I'm not saying either one is good for you, only that people frequently assume that since epoxy has very little odor it must be less harmful.

Many fiberglass shops don't like to bring epoxies in because they've had employees develop sensitivity to it in the past. There is a different mindset in an epoxy shop and much more money and time is spent making sure you don't get it on you and controlling the shop conditions.

 

[ondarvr]

Re: Treated plywood

Closed cell and moisture content mostly. Check post #11. I also wouldn't use it in or around aluminum period!



Neither are as safe as mother's milk that is for sure, but using the correct PPG, it shouldn't be an issue with either unless someone is gonna try and cowboy it in with bare hands and chew it like dip.

Moisture content is not an issue in the PT we're discussing, it's kiln dried and made out of a better than average ply, it's designed and sold just for this application. You are assuming this PT is similar in some way to the stuff from a big box store.


For several decades there was no PPE used in the fiberglass industry, even then people didn't have signs of problems from being around it. In the fiberglass industry it was the drugs, alcohol and general life style that killed people, not the resin.

 

[ondarvr]

Re: Treated plywood

One thing I can say is ive become sensitized to epoxy during this build...it started out as just split finger tips, but by now, if im not real careful during a session, both my hands get covered in rash that lasts a week....it dies down when away from it, but hasn't completely redacted...I may be forced to use poly on my next build.

This is far more common than people think, several people on this site have reported it over the years.

 

[bgc]

Re: Treated plywood

I wouldn't have felt comfortable using the interior grade plywood no matter how it was sealed. How much maintenance does it require bgc and did you do anything after the glassing, i.e. paint, gelcoat?

I dont do anything special with the glassed wood and only covered with carpet. The plywood on a Starcraft Jet Star is not structural, just for comfort.