How good is a polyurethane anyway?

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So I've got my raw hard maple butcher block countertops and I've been experimenting with poly finishes on the underside. I have been using Minwax clear and satin oil based poly, trying some patches of wood with full strength and some with poly diluted with mineral spirits. So far I don't see much difference between the two although the diluted obviously goes on thinner. I have 3 coats of clear poly full strength and it doesn't look all that different from the diluted test patch, except you can feel the difference to the touch. I'm beginning to wonder what the point is if I put on 3 full strength or 6 diluted and end up with the same thing? I'm concerned that too few coats of diluted poly won't provide the protection I need. How do you know when enough is enough, and is it usually recommended to lightly sand the final satin poly coat?
And finally, concerning wood protection I am finding out just now that poly isn't really impervious to liquids. I'm hearing from Minwax directly that the oil poly is more resistant than water based, but it is not going to protect the wood from all liquids such as a wet glass of ice water. Now I'm wondering if I'm barking up the wrong tree with poly. I'm being told now that the only true ironclad treatment to protect the wood is conversion varnish that has to be applied with a compressed air spray application, which I cannot really do practically. I've called a couple of guys to get a price on this, but may just end up with the poly after all, and I guess just cross my fingers that the poly will do OK. Maybe I need a couple of extra coats...
Any thoughts or advice on this long winded message are appreciated.
dwhite
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Dan White wrote:

I think the main idea behind thinning poly is to make the results look more like shellac. Not dipped in plastic, but sort of hugging the grain and showing off your good surface preparation, instead of burying it under a layer of amber goo.

I wouldn't worry too much about this. I used poly on my first full-scale project, what feels like three lifetimes ago. It's a plant stand. The plants regularly "pee" on it, and I designed the shelves so that they would trap any spillage and keep it from leaking onto the floor. I try to mop up spills, but this thing has been exposed to plenty of pot overflows that went un-noticed, and it still looks spiffy keen going on a decade later. (Spiffy keen to the extent that it can, mind you. I've learned a lot since this project.)
Unless you're building a boat, poly is probably fine. It will withstand moisture abuse much better than shellac or lacquer. Though don't discount all the other possibilities I haven't mentioned. There are more finishes than you can shake a stick at, as someone will probably be along to tell you about shortly.
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more
I understand, but how do you know when enough is enough? I'm thinning maybe 25% or so.

that
would
up
since
that's good to hear. I'm thinking I should use the poly in any case and deal with any problems down the road. I really don't want to spend more $$$ than I have on professional spraying of this conversion varnish. Maybe Minwax thought I was going to leave coffee and water on the counters for a week?
thanks, dwhite
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maybe
You can thin poly 50% if you want to - it won't hurt a thing. It will take more coats to get a build up but it won't hurt anything.

$$$
Stop by some local bars. The small ones. It's very common for small bars to build a bar out of some stuff and then pour the poly to it. I mean pour. They'll end up with a really plastic finish on the top of the bar. Hard as it may be to believe, the patrons in these establishments often spill water (yeah, right...), alcohol, beer, and Budweiser on these bar tops. Equally hard as it may be to believe the sexy wench behind the bar may sometimes be too wrapped up in the advances of the "my-god-you're-beautiful, my-wife-doesn't-understand-me" idiot on the other side of the bar to notice, and the puddles can lay there for a while. One wipe with a wet bar rag and it's a brand new bar. Well - at least under the same lights that made that toothless, tattooed, what-ever-it-is behind the bar appear to be a sexy wench.
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On Fri, 12 Nov 2004 13:18:41 GMT, "Mike Marlow"

This is not polyurethane, but a two-part heavy build epoxy finish that usually levels to about 1/16" to 1/8" thick per coat. It is very strong and totally waterproof (and 'mostly' solvent-proof, acetone and some of the heavier paint removers will damage it after prolonged exposure). The application of which I explained in another recent thread. While this stuff is good, it also leaves the aforementioned 'plastic' look, and while not difficult to apply if done right, is time-consuming. If damaged it can be recoated to fix the blemishes, but you have to recoat the whole surface, and this also makes it another 1/16" thick or so. This looks silly rather fast.
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be
notice,
and
that
I'm still trying to hire a sexy wench for the counter. Good for business, ya' know?
dwhite
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Turn down the lights and you can get away with an ugly one. They're cheaper too.
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Minwax
all
put
I
recommended
poly
I'm
a
just
Dan, I built a wooden island top for my new kitchen -- the wood was bubinga. When searching for a finish I settled on Tung Oil (Pure -- not the "finish" kind). I was told that it was food safe (once cured) and that it would not show water marks. After four months of use I am still happy. We have no water rings nor major damage although we use it everyday.
The Tung oil finish is also easier to fix -- when first applying the finish I noted a spot where I did not quite get all the clue up during the contruction -- took out my handy scraper and shaved the glue and a few angstroms of wood -- reapplied the Tung Oil and you can never tell where the spot was
BTW I had to mail order the Tung Oil -- I could not find it at either of the BORGs -- they only had "Tung Oil Finish"
Check out the following for some more thoughts http://www.craft-art.com/index.php?PAGE=HOME&SESSID d514f09440086214b847a7380a796a
HTH Cheers
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I wouldn't use thinner either. YOu want a good coverage and that'll take too many coats. Jana
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Is the varathane Sherwin Williams' brand of poly? I've been doing some testing on my counter bottoms and will go pick up some of this stuff and try it out.
thanks! dwhite
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Varathane is a RUSTOLEUM CORP trademark.
In oil-based (I'm old-fashioned) polyurethanes, Benjamin Moore and ZAR are good stuff.
Also try, Behlen's Rock Hard Table Top Varnish. It is *not* a polyurethane, _Very_ durable.
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Those Behlen folks have a web site? DAGS and came up dry.
bob g.
Robert Bonomi wrote:

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To answer the subject: Where do you suppose the term "wrap it in Saran" came from? Ayup, someone painted thick coats of poly all over something and made it look just like plastic.
On Sat, 13 Nov 2004 19:41:01 -0600, Robert Galloway
http://www.google.com/search?q hlen&sourceid=firefox&start=0&start=0&ie=utf-8&oe=utf-8 Results 1 - 100 of about 38,000 for behlen. (0.62 seconds)
Try connecting to the Internet FIRST next time, eh?
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Your Google must be broken! Try "Behlen finishes". The first link on the right is to Woodworker.com...
David
Robert Galloway wrote:

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try
polyurethane,
Anybody else use Sherwin Williams? There's a SW store nearby me and it would be convenient for me to use them rather than go ordering something online and then finding I don't have enough. (I have lots of wood to finish.)
dwhite
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Dan White wrote:

If you're in the US the BORG generally have Varathane in stock.

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I was at Home Depot today but couldn't find any Varathane. I did find spar varnish (marine) and wondered whether that might do the same job as the clear poly but maybe be even tougher against water spills? Any downside to using this stuff instead of poly?
dwhite
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Dan,
If I recall, this is a commercial establishment. Even so, it depends on the type of traffic you will have on these counters. If you are serving food on them and wiping them down several times a day, or if they are at the cash register whit goods beings shuffled across them all the time, then you should go with a conversion varnish or other hard ass finish.
Assuming, they are more of display counters, then poly will be fine. Regarding how much and what method these are the decision criteria.
Wiping is the easiest way for a non-professional to end up with professional results. By appling super thined coats you don't have the opportunity for sags, runs or thready brush marks. If you can get the look you want with brushing, then that will save you time and get a better build up.
If you can stand the plastic feel, it's probably best to put lots of coats.
Regarding sanding. If you are brushing on thick coats, you may need to sand between coats. Poly coats sit on top of each other they don't melt into each other. However, if you brush the next coat before that last one has fully cured, there is no need to sand. Most cans will give you the time lines.
Final sanding depends on how smooth you applied it in the first place and how flat you want it. Once you have lots of coats, you can use some 400 to really smooth it out with some wet sanding. Then apply a last coat and it;s like ice. You can also use 0000 steel wool and some wax to seal the finish and control the gloss.
Depending on how you stuff is used wax might be more trouble than its worth. It really makes thigs look nice but requires some maintenance. Although in some case, wax is exactly how you keep it looking nice for ever. Just buff once a week.

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Minwax
don't
on
all
put
protection I

recommended
poly
that
I'm
now
get a

just
extra
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Dan,
I think you have the right idea. Poly for the people and raw for the food prep. I would not wax the tops as it will just cause problems with moisture getting caught in the finish and require buffing all the time. Th only danger os very hot liquids sitting in place can cause some blush but it would take some pretty hot stuff so you're likely OK.
To keep the health department happy, you should find a butcher supply vendor. They will have a specifc wood block sanitizer/conditioner you can use weekly or so.
The smart health inspectors will know that studies have show that wood has properties that actually kill bacteria. Something at the cellular level of wood, for its natural defenses, actually ruptures the cell walls of bacteria so it can't sustain life on wood. Plastic cutting boards actually harbor bacteria in down in the scratches that even a wash with hot, soapy, and bleach solutions can't easily kill.
BW

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