Uneven polyurethane finish

Hello all,

I am a furniture finisher novice. I need to protect a dining room table from water marks caused by glass condensation. I know I need to probably apply 3 coats of polyurethane with satin being my luster of choice. To practice for this I applied 2 coats of Varathane oil based polyurethane via brush to a small end table. The result was awful. The polyurethane was very thick but the can said to not thin the product, so I didn't. The finish did not self-level and therefore has a thick wood grain type finish to it (but it is not from the grain below).

Not wanting to ruin a small coffee table I took it to a furniture refinisher to apply 3 coats of satin oil based polyurethane to it. When I picked it up it was smooth as glass. I asked him if he used wipe-on poly and he said that he used a brush. I picked his brain a bit more but I could tell he didn't want to tell me his process.

Now I getting ready to finish the dining room table mentioned above but I am afraid to start because of the bad results I have had. Does anybody have any words of wisdom they could share to help me get a smooth finish?

TIA,
Blane

 

Poly can usually be thinned a little bit. In fact, poly labeled for wiping usually has been. One of the problems I see when people apply poly is they tend to over-work it. Additionally, a light scuff sanding with removal of the sanding dust needs to occur between coats to promote adhesion of the layers.

 

You need to have the right brush also. With oil base varnish/poly that would be a natural bristle [hog hair] brush.

 

Also known as a China bristle brush.

If you are starting with bare wood that has been stained, you usually want to apply a sanding sealer first. It also needs to be a product that is compatible with your finish... I'm this case poly. The sanding sealer can also usually be made by thinning your poly 50:50. (This is a good reason not to thin the poly you use as your finish excessively- it may not be as hard of a finish if you thin it too much!)

If you are going over a previous and unknown finish, you might want to apply a coat of sealer such as Zinsser Seal Coat, which is a dewaxed shellac, which provides a good bond between 2 dissimilar finishes (Your poly and whatever was used before you).

But imo, no way I would be brushing furniture. Furniture quality finishes can usually only be achieved with spray equipment.

 

Go find a Woodcrafters store and pick up a high quality water based urethane that is made for furniture and quit using that general use oil based stuff.

You will be amazed at the quality of the finish!

 

Thank you all for your helpful replies. I gather the following:

1. Despite what the can states it sounds like thinning it is what I need to do to allow it to self-level.

2. I will be applying the polyurethane over an unknown finish so I will first put a coat of Zinnser Seal Coat.

3. I will use a natural bristle brush (I think I did but I will confirm).

4. I will do a light sanding between coats for adhesion.

5. I understand to get the best quality finish I would need to spray but this table is going in our vacation rental and therefore a brush finish is good enough, especially after seeing what the furniture refinisher guy did with a brush on another table.

6. Water based poly. The refinisher I went to said water doesn't hold up as well as oil. I also read that online. Perhaps the high quality one you reference does. What brand do you recommend? What is the advantage of water based besides no VOC's and water cleanup?

Thanks again,
Blane

 

I have limited experience with water based polys although I did use one that was a 2 part [catalyst] that seemed to hold up well. I don't remember the brand name.

Generally speaking oil base coatings dry to a harder film than their latex counterpart. Oil base poly will deepen the stain and/or colors naturally in the wood. Water based polys don't change the color any - just give it a sheen. Water based polys dry quicker.
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The best thing about any oil based product is that it's supposed to be slower drying so it can self level. Water based coatings often get tacky quickly and so if you are brushing it can leave brush strokes if you don't work quickly or if you overbrush it. You don't want to overbrusg any type of finish.

 

I've switched to just about only latex/water based paints but I'm still an oil based poly guy.

 

Please tell me this wasn't your local big box store paint "pro"!

You can debate all you want but until you give it a try I can only make suggestions.

Water based products like anything new have their growing pains and it takes a lot of time to reverse initial performance flaws.

Hope you all know your car is now painted with water based paints!

Brand is "General"!

 

Hello all,

Thank you for all the follow-up replies and for the brand name. I think I have enough information to try again. I sure hope I get better results that my first venture into using polyurethane to protect a table top.

Blane

 

I switched to Min-Wax wipe on poly several years ago for most of my projects. I rarely brush a finish on.

 

I've never used the wipe on poly, since it's thin I assume it requires more coats to build up the finish ??

 

Hello all,

I took all the advice given above and ended up with great results on my dining room table. I think the biggest help came from the quality of the polyurethane I brushed on (4 coats). I used General Finishes water based satin finish.

I am very happy. Thanks again for all the help.

Blane