Spar urethane on wooden countertop with sink?

Hi guys i just wrote a long post and it ended up disappearing after needing to log back in to post.

Im going to keep this one short...

Im planning on a wooden countertop plus sink project for the kitchen and would like to know the best protective finish.

There are many DIYers online that used waterlox or mineral oil, or urethane, or combination of waterlox and urethane, and all of them do not completely protect the wood from water spots and damage in the long run.

I searched and read around the web but i cant seem to find a good example of spar urethane on countertop, even though it says on the label its superior protection against the elements, indoor/outdoor.

The question is
Is spar urethane a good way to seal the wood?

I bought a can of minwax helmsman spar urethane and would like to make sure before i open it.
They also had minwax pro series spar urethane which is water based for $1 more.

I was also wondering how the super pricey professional custom made butcherblock with undermount sink i see in luxury homes are finished.

Thanks as always!

 

Spar polys and varnishes don't dry to as hard a film as their interior counterpart and wouldn't be as good for an interior finish. Interior poly will wear better. A wood top w/sink isn't a great idea. The areas prone to water damage will be between the boards [the gap will open/close enough to get wet at times] and the edges covered by the sink.

 

I don't know too much about it, but you could check out a bar top finish.
The bar top (epoxy?) looks almost like a sheet of glass.

If nothing else, Varathane Diamond dries to a hard finish and is crystal clear.

 

Oil based polyurethane would be my choice (you'll hear some object to this saying it's not food-safe but it is once the poly is cured). Three coats minimum with a light scuff sand and sanding dust removal between coats.

 

Thanks for the input guys,
I started coating one of the smaller counters just to see what happens with the spar since that's what minwax recommended, but so far it goes on thick but also dries soft just like marksr said.

Hard enough to sand but the sand block gets caked since it's semi tacky. I just read somewhere that "spar" varnish is made for wood that expands due to the environment, so it's made not to cure too hard.

Also a bunch of micro bubbles formed even though I thinned it 1/4, used a pricy thick natural brush and made sure not induce air etc etc. It will go on bubbleless but after a while it will be filled with tiny bubbles, so im guessing its gasses from the wood itself? (Birch btw).
How do I avoid that?

If the spar urethane doesn't work out I will go with the basic oil polyurethane next.

 

It takes 3 coats to get a nice durable finish. I wouldn't get concerned about the bubbles just yet. If they are there after the 2nd coat I would be. Sanding between coats is best and should take care of the ones you currently have.

 

Thanks for the reply marksr,

Im getting mixed results on so far, and its driving me nuts.

Im still testing the coats on the 2 of the smaller countertops. The bubbles that i thought was the problem seems to be dust nibs since i think ive mastered how to apply a coat without any bubbles by now. and the tiny bumps always appear after i make sure there no bubbles. Also the tiny lumps seems random without anything visible inside.

Im also experiencing uneven coats, even though it goes on flat, by the time it starts drying there are high spots and low spots like a topographic map.

I've also tried the oil based poly on a scrap piece but same results but it dries alot harder.

It also doesnt help that it rains almost everyday and im doing everything in the living room.

If everything fails i'll strip everything down and re-stain and just go with a wipe-on method with waterlox.

 

The bumps could be some dust. Are you vacuuming and wiping the wood with a tack cloth? If you're seeing 'topographical' areas it wasn't smooth before the coat was applied....the whole thing will not re-level. If you want a really tough oil based poly try Last N Last Flooring poly. I've gone back to use previously opened cans of Last N Last and Minwax and the skin formed in the Last N Last is a whole lot tougher than the Minwax. The flooring poly is a lot thicker but once applied and dried you won't notice a difference other than toughness.

 

Yes I've done everything i could to minimize the dust, I turn the A/C off, use tack cloth use a fresh batch of spar urethane etc etc. hopefully i can sand it down evenly the next attempt...

I thought about going with floor poly since i figured they should be the most durable since it deals with foot traffic. I'll check out last n last, once i give up on the spar urethane.

The funny thing is before i started this project, I've only found negative stuff about the use of waterlox and other polyurethane on a wooden countertop with water hazards, so i ended up going with minwax's spar urethane infograph at lowes that said its best for countertops.

Now after having a hard time with the spar urethane I'm beginning to find alot more blogs of people having great results with waterlox and how easy it is to apply them the first try.

Its one of those things where you got to search the right questions to get the right answer on the internet.

The helmsman spar urethane isnt bad at all, it does make the wood virtually waterproof (I left a pool of water overnight with no problem), and it has a nice gloss, but the application drives me nuts, at least for a DIYer without professional tools and work area.

Once the last coat I did hardens enough to sand in maybe 2-3 days i'll decide whether to give up or not.

 

Some of the high/low sheen areas can be attributed to the wood sucking up the poly. Softer spots in the wood won't retain an even shine until they are sealed. Generally it takes 3 coats [sanding between coats] to get a nice even sheen.