# Do Not Thin



## Murphy's Law (Dec 15, 2011)

I bought a gallon of a new-for-me brand (ZAR Ultra) of exterior oil-based Polyurethane clear satin finish.

I'm attempting to eliminate the need for Thompson's Waterseal weather protectant or other brand every year on an old fishing shelter on our pond. I have screwed-n-glued new CDX 1/2" plywood onto the old flooring and I don't want the weather to ruin the new floor.

I usually thin poly to 50/50 on the first coat for outdoor applications for deep penetration. Then I apply a full strength top coat after 24 hours. This has always worked very good for me. The beauty of a fine poly finish is not important here. In fact, I don't want to create a slick surface for safety reasons.

This new can has in bold letters "DO NOT THIN" in the instructions. Do you guys think I should not thin this stuff for my first coat? I paid $45 for this gallon (ouch!) and I wouldn't be a bit shy about returning it if it doesn't appear to meet my needs.

What say ye?


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## cabinetman (Jul 5, 2007)

Murphy's Law said:


> I bought a gallon of a new-for-me brand (ZAR Ultra) of exterior oil-based Polyurethane clear satin finish.
> 
> I'm attempting to eliminate the need for Thompson's Waterseal weather protectant or other brand every year on an old fishing shelter on our pond. I have screwed-n-glued new CDX 1/2" plywood onto the old flooring and I don't want the weather to ruin the new floor.
> 
> ...



Al that likely means is that it's ready to use out of the can...as is. 










 







.


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## Steve Neul (Sep 2, 2011)

I imagine the problem is if they said to thin it people would thin all the coats and the stuff will work better unthinned. There would be nothing wrong with thinning the poly except I think 50/50 is too much. I wouldn't thin it more than 20% because if you thin it too much it breaks down the integerity of the urethane and that's the foundation of the finish. I often thin poly to spray it but I thin it as little as possible and still spray it.


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## chemmy (Dec 13, 2011)

It's always good to make an inquiry to the company as to why they warn not to thin, many times it is due to solvent tolerance issues or types of solvents that may affect the performance of the coating, as well as others..just like in lacquer where to much xylol will knock the cotton out of solution creating a white gelatinous mass to form.
better to know than guess.


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## HowardAcheson (Nov 25, 2011)

A finish manufacturers are reformulating their products to reduce or remove VOC's. To sell their products in many areas the products must meet local, state or federal guidelines or regulations out of the can.

The reason for the "Do Not Thin" is because that would cause their products to exceed the VOC emissions. As a manufacturer, they can't encourage or suggest adding more VOC emitting chemicals to their product. That said, what you do in the privacy of you own shop is up to you. If you want to thin, you can. However, some of the chemicals being substituted for the traditional thinners do not always play nice with the traditional thinners. Always test out any mixture you brew up yourself.


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## chemmy (Dec 13, 2011)

I see nothing on the MSDS that would indicate non use in any areas, but i also don't see any diluent or solvent listed that would ban the use of dilution, even though it already is only 45% solids to begin with, thus, i would still contact and inquiry as to why they state not to, if for no other reason than to know.


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## Murphy's Law (Dec 15, 2011)

Steve Neul said:


> I imagine the problem is if they said to thin it people would thin all the coats and the stuff will work better unthinned. There would be nothing wrong with thinning the poly except I think 50/50 is too much. I wouldn't thin it more than 20% because if you thin it too much it breaks down the integerity of the urethane and that's the foundation of the finish. I often thin poly to spray it but I thin it as little as possible and still spray it.


Yeah Steve, you're right. I usually only thin enough to allow a good spray pattern. Probably 80/20 is more like it.



chemmy said:


> It's always good to make an inquiry to the company as to why they warn not to thin, many times it is due to solvent tolerance issues or types of solvents that may affect the performance of the coating, as well as others..just like in lacquer where to much xylol will knock the cotton out of solution creating a white gelatinous mass to form.
> better to know than guess.


Hmmmm. I didn't give the non-compatability issue a thought. Thanks.


HowardAcheson said:


> A finish manufacturers are reformulating their products to reduce or remove VOC's. To sell their products in many areas the products must meet local, state or federal guidelines or regulations out of the can.
> 
> The reason for the "Do Not Thin" is because that would cause their products to exceed the VOC emissions. As a manufacturer, they can't encourage or suggest adding more VOC emitting chemicals to their product. That said, what you do in the privacy of you own shop is up to you. If you want to thin, you can. However, some of the chemicals being substituted for the traditional thinners do not always play nice with the traditional thinners. Always test out any mixture you brew up yourself.


Another good point. That's exactly why we're seeing more and more water based products on the market. Good call. Just look at all the 1990s automobiles with terrible paint jobs. They were (and still are) experimenting with different low VOC finishes during that time period.



chemmy said:


> I see nothing on the MSDS that would indicate non use in any areas, but i also don't see any diluent or solvent listed that would ban the use of dilution, even though it already is only 45% solids to begin with, thus, i would still contact and inquiry as to why they state not to, if for no other reason than to know.


Thanks.

I think there is an email address and a phone number on the can. I'll ask the company. Thanks everyone.


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## Tennessee Tim (Dec 15, 2010)

CDX :blink:.... C grade on best face (If you call it a good side)...D grade on back.....X anything goes in the middle INCLUDING voids and air pockets!!!! NOT on my jobsites.

I really wish you the best ..... you'll probably have more trouble out of the plywood than anything, even with the best finish. It's a highly sold grade of plywood not intended for most uses ESPECIALLY roofs and floors (drive through the nieghborhood and notice the dips/waves from rafter to rafter...under thickness and wrong plywood grade). Doesn't tolerate weather or walking very good due to the plys not always contacting/being glued to another ply/void.

:thumbsup: You did glue it and screw it :thumbsup:.

I'm with Chemmy...contact the manufactor...leaves NO QUESTION(s).

Have a Blessed day in Jesus's Awesome Love,
Tim


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## HowardAcheson (Nov 25, 2011)

>>>> I see nothing on the MSDS that would indicate non use in any areas,

No reason to put that info on the MSDS but the VOC emission. data is on the sheet. The majority of the VOC regulations are local or area based and are changing frequently. That's the reason many finishing products are no longer sold in southern California or the NYC area. In those areas the VOC regulations are the most strict.

Contact any major finish manufacturer to verify


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## chemmy (Dec 13, 2011)

HowardAcheson said:


> >>>> I see nothing on the MSDS that would indicate non use in any areas,
> 
> No reason to put that info on the MSDS but the VOC emission. data is on the sheet. The majority of the VOC regulations are local or area based and are changing frequently. That's the reason many finishing products are no longer sold in southern California or the NYC area. In those areas the VOC regulations are the most strict.
> 
> Contact any major finish manufacturer to verify


Not necessary howie, i will take it you have done so already.


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## HowardAcheson (Nov 25, 2011)

>>>> i will take it you have done so already.

Sure I've thinned oil based finishes and continue to do so. I live in North Carolina and there are currently no VOC regulations in effect. But I used to live outside NYC where VOC regulations are in effect and thinned most of my oil based finishes at least 20% for the initial coat and 10% for subsequent coats. Non-commercial use of finishes were not regulated.


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## Getting better (Dec 3, 2009)

I've been told that the "do not thin" label is a legal requirement for low VOC compliance


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## Murphy's Law (Dec 15, 2011)

I talked to someone at ULG, the manufacturer of the ZAR Ultra, and he was very illusive with his answer. He said that lots of folks do thin the Ultra product for the first coat but the company could not recommend it. He would not offer any recommendations on max. thinner usage either. I asked if there was any concern about chemical conflict with thinners and he could not answer.

When I asked him if he had any idea what product we were discussing he politely asked if there were any more questions and I told him no. Whatever they pay that guy, it's too much.

I returned the Poly to the store and I have decided to remove the old 3/4" plywood and install new 5/4 PT decking wood. After all it's only an 8'x12' fishing deck with a tin roof and a 16' pier.


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## Tennessee Tim (Dec 15, 2010)

I'm CONFUSED:blink::huh:....I thought it was 1/2" CDX screwed and glued....
(1st post).... "I have screwed-n-glued new CDX 1/2" plywood onto the old flooring and I don't want the weather to ruin the new floor.
" 
(last post)...."I returned the Poly to the store and I have decided to remove the old 3/4" plywood and install new 5/4 PT decking wood. After all it's only an 8'x12' fishing deck with a tin roof and a 16' pier. "

Have a Blessed day in Jesus's Awesome Love,
Tim


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## Murphy's Law (Dec 15, 2011)

Tennessee Tim said:


> I'm CONFUSED:blink::huh:....I thought it was 1/2" CDX screwed and glued....
> (1st post).... "I have screwed-n-glued new CDX 1/2" plywood onto the old flooring and I don't want the weather to ruin the new floor.
> "
> (last post)...."I returned the Poly to the store and I have decided to remove the old 3/4" plywood and install new 5/4 PT decking wood. After all it's only an 8'x12' fishing deck with a tin roof and a 16' pier. "
> ...


Sorry - I didn't make it very clear. :blink:

The old existing floor on the deck is 3/4" plywood. It has been on there for at least 12 years and looking pretty bad. I purchased 3 sheets of 1/2" CDX to put over the old 3/4" wood. I screwed-n-glued the new 1/2" CDX on top of the old 3/4" deck. Now I'm considering removing the new AND the old plywood from the joists and putting new 5/4 deck on the joists. This would make the floor on the shed match the deck on the dock. We use this shed to clean fish (and any other animals during hunting season) and since it is about 600 ft. out in the back of the house we do not have electricity or water out there. I keep a bucket out there for rinsing the floor but sometimes the deck doesn't get cleaned very well after being doused with blood and guts. So I thought a couple of coats of a good marine polyurethane would be nice. But a PT deck will be OK, too.

I can always use the three 4'x8' (now 1.25" thick) plywood sheets somewhere else here on the farm. I always have a project list as long as my arm. In fact the extra thick plywood may become a new roof on a tornado damaged chicken coop.


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## Tennessee Tim (Dec 15, 2010)

The PT will probably work better due to the cracks and easier to rinse and maintain.

I've seen some docks around here have the old style (they still make them new) hand well pumps on their docks with a pipe down into the water to draw from. They're not pressure units but can get some volume to clean with and saves carrying lots of water.... remove or drain in winter:laughing::yes:.

I believe your on a better long term plan with the PT.

Have a Blessed day in Jesus's Awesome Love and be safe over the water,
Tim


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