achieving noticeable depth with polyurethane?
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Replies
I'm going to try not to trigger the silly spam filter. Don't use poly. Use a phenolic resin varnish. For a lighter colored varnish that will yellow less use a soya/alkyd varnish.
Behlen Rockhard is a phenolic resin varnish--so is Waterlox Gloss. Pratt & Lambert 38 is a soya/alkyd varnish.
Epoxy does yellow, it also will crack and be a bear to remove and impossible to fix other wise.
Something to keep in mind is that any oil based varnish will have some amber coloring to it. An alkyd resin/soya oil varnish will have the least amber and a phenolic resin based varnish will have the most.
What is wrong with polyurethane? Also, I think I should redefine my question because a lot of vendors seem to be getting the wrong message. I want to achieve a depth on top of the surface of the wood. Almost like putting glass on top except I don't want glass on top...I want something that will both seal the table, protect the table, and let the natural beauty of the wood show through.
This is my first wood working project so I apologize to everyone when I ask silly questions.
you cannot achieve with poly that you can with the others. can you perhaps consider that. you asked and you got good replies.
if you don't want those answers then don't ask the question. sems that you have your mind made up and you just want everyone to agree with you
ron
That is a very good question as a matter of fact.
>What is wrong with polyurethane?<
Some say it is evil, some use it on the sly and poo poo it in print ; but I won't get all into that.
For your purpose : a thick, relatively clear, uncolored layer over the wood then this is the problem with poly for your specific project . . .
each THIN layer must be allowed to dry fairly well before the next layer is applied. It will take many, many, many, many layers to build to a thing that you can look down through to the wood surface. Putting more layers on top without allowing each to dry ENOUGH will make a layer of clear rubber that you will hate. It won't dry. Each layer can take a day or two to dry. Even more depending on the temp of your shop and other factors.
I know the kind of surface you are speaking of. One of my favorite restaurants back in the day had tables like this. Things were "decoupaged" way down in the finish to look at etc. It was interesting.
The way this was done was with a sister product of polyurethane. This product is epoxy. There are epoxy products that definitely should not be used this way and others that are formulated just for this purpose.
Keep in mind when we speak of "depth" in this forum, and in any fine woodworking forum, they/we are referring to looking down into the depth of the wood its self. Down through the cells of the wood. Not every species will look this way. In fact many planks of the same species may have no depth at all. Depth is a perk and is only found in some planks.
I have just tons of depth on my dining room table and I can still see the pores of the grain in the finish. Most of the finish is soaked in below the surface of the wood. Well the important depth enhancing part of the finish anyway.
I almost recommended glass. Glad I didn't.
Epoxy my friend.
Epoxy
It has hardeners and can "cure", not dry, in a thick layer. Meaning poly, for the most part, needs to be exposed to oxygen to oxidize before the next layer goes on. Epoxy hardens by cross linking even in the relative absence of oxygen. Under water for instance
I agree about the epoxy being a bad idea, generally, as a wood finish. Listen to these guys about the yellowing, and difficulty of repair.
However . . .
The tables in the restaurant that I mentioned were just fine.
Part of the reason was they didn't see the direct light of day. They were in a location with dim light and not in hot direct sun coming through windows to yellow the finish and buckle it when the wood dried out too much.
If you insist and understand the limitations then . . .
http://www.systemthree.com/store/pc/Clear-Coat-c14.htm
Also check these guys out
http://www.westsystem.com/ss/
These guys have thin books about using epoxy.
READ THEM or proceed at your own peril.
I am not kidding. These resins can be dangerous, expensive and destructive. Burn your shop down destructive.
Ruin your health and or vision for life dangerous.
Cool stuff though if used right.
I reread your original and so may as well hog further
>noticeable depth with a polyurethane and if so, how many coats<
20, 30 . . . 50 coats if you want that "oh look a thick layer over the wood " kind of finish.
times days between each coat. It could get nuts.
Take a scrap and go at it and just see for your self. Assuming you have some time to learn and experiment.
I took a winter developing the finish for my dining table before I began on the table its self.
I was a rank beginner and I was not trying to make money/sell the table.
I am happy I took it slow.
To answer your question "What
To answer your question "What is wrong with poly?"
Around here it's a dirty word, and you will be roundly chastised for even considering it. So just to take the other side of the tracks;
If you are looking to apply it use three to four thin coats. You'll find that sanding it well in between coats will ultimately produce a flatter overall finish. Depending on the thickness of your coat use 220 or 320 to sand. This will promote clarity and depth. Just be careful with your sanding between coats. Think of hills and valleys. When you initially sand you'll see some dull areas, these are the tops of the hills being cut. The shiny areas are the untouched valleys. Now go easy with your sanding and you'll see more dull areas and less shine If it's 90% dull you're fine.. Be careful; you don't want to sand it so far as to cut into the layer underneath. If you do you'll have a witness line and that's a discussion unto itself.
Oil finishes will change over time, that's a fact. When you hear "poly will yellow" believe me it's not overnight or that drastic. Chances are you won't notice it, especially if it's over a darker color. I still have the first piece I ever finished, a small mahogany chest of drawers. What did I use to finish it?. Horrors, polyurethane! I've never had to touch it and the finish is over 25 years old.
Poly does have it's drawbacks to be sure, but if you're just starting out you'll use it and wonder what all the fuss is about.
Good luck,
PG
There
I found a minute to go further into this poly coat
I know the 20, 30 . . . 50 coats sounds preposterous. So I looked up some facts for you
OK for instance
Bob Flexner calls a single coat of properly applied dried finish for poly about two mils thick
.002 inch
Lets say you call a thick, deep clear coat over your coffee table 1/16 inch thick.
I am positive the thick coated tables I saw in the restaurant had a much thicker clear coat.
It would take at least 31 layers of finish at 2 mils each to make a 1/16 inch thick clear coat. That is assuming you didn't sand it at all. If you are sanding now and then between coats then many more coats would be required to make up the thickness.
Not that this is a good idea. No it is not but you get the idea.
Applying thicker single coats, according to Bob Flexner, are going to get wavy and cause problems so you really can't apply the finish much thicker than 4 mils when wet which dries to roughly 2 mils when dry.
I must be an offender , so be it ... I have achieved excellent results with minwax wipe on satin poly. What i do is sand down to 400 depth is all in the prep. After sanding I tack rag the surface clean . the poly dries quickly so using a rag to wipe a large flat surface is a futile mistake. what I do is wrap a tite nap glue roller ... (think paint roller tube they make the for contact cement as well ...) with cotton rag then pour some poly the short distance across the table top then quickly squeegee the poly down the length of the top. do not over wipe minimal passes are the trick while poly is wet... the temptation to re wipe streaks must be avoided, let it dry lightly sand and repeat process 5 or 6 times to desired luster. i have used this method many a time and the finish is plenty durable. the pic of this table were done in 100 degree temps . When wrapping thr roller stretch the cotton rag an wrap around at two times.. tuck excess at end into roller tube , you do not want ends dragging. good luck.. just for clarification you are hand holding the tube and using it like a squeegee. and not using a roller frame.
tom
Well, just as a comment, I am sure you have gotten a "good" finish with your poly application. Whether it would be a finish I would prefer as being more "in the wood" look or a sheen of "plastic" sitting on top of the wood would be the interpretation.
Your application method is interesting but no easier than just using a cloth and wiping it on. And sanding to 400 can be problematic by actually burnishing the wood so the finish may not even penetrate. Just another opinion.
It is easy to make your own wipe on varnish by thinning (for me) non-poly oil varnish half and half with mineral spirits. No point in paying the store for diluted product.
Opinions always welcome
Hey Gretchen, Thanks for posting, Can't say I have ever had a problem with finish coming off a project due to burnishing the wood , Although I do understand the logic.
I really do not mind buying the diluted product , with the poly in it ... 20.00$ is the price of convenience.
Will a dilluted varnish with out poly offer the same protection as one with?,
I would not try to wipe a 4x8 table with diluted poly on a rag on a warm day and would not recommend it .
Tom
Yes, it will offer equal protective power. And I have done large surfaces with a cloth. There aren't "witness" lines, because when you repeat the application you cover "holidays", etc. It would be a much more even application than your squeegee, but if you are "satisfied" that is OK..
As for cost, you are paying the equivalent of $40 for your "varnish". It's pretty easy to pour and 'eyeball' --it isn't a magic number.
There is little doubt that when I am shopping at an antique show, or such, I can spot a poly finish. It is definitely different.
I also think I see a good bit of sheen on your table that is a "satin" finish. Maybe it is just the picture.
I didn't say the finish will come off of a burnished wood--just not be absorbed in the wood.
Opinions always welcome
Hey Gretchen, Thanks for posting, Can't say I have ever had a problem with finish coming off a project due to burnishing the wood , Although I do understand the logic.
I really do not mind buying the diluted product , with the poly in it ... 20.00$ is the price of convenience.
Will a dilluted varnish with out poly offer the same protection as one with?,
I would not try to wipe a 4x8 table with diluted poly on a rag on a warm day and would not recommend it .
Tom
Just re-read the op's post and believe we are both off topic , sounds to me like he is looking for a thick bar type finish.
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