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Old 3rd August 2006, 08:46 PM   #1
Vikash is offline Vikash  United Kingdom
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Default Birch plywood finishing

How do you finish good quality plywood?

Using russian birch ply I've sanded down with 180 grit and applied danish oil which results in a blotchy finish. Trying it over an undiluted pva base makes the finish even but with a bad surface finish.

Is the best method to apply many diluted pva/water coats and sand down each coat etc. before applying any oils/waxes?

Please share your favourite method of finishing ply to give me some inspiration!

The 1/4 slice is the one applied over the PVA.
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Old 3rd August 2006, 09:15 PM   #2
poobah is offline poobah  United States
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Don't like the 1/4" slice...

What's wrong with tht 3/4" slice? Looks gorgeous though just like that!

The blotchiness you describe may be tearing in the grain. Plywoods are prone to this because they are peeled and not oringinally flat. I suspect this because the light spots do seem to follow a certain alignment in the grain.

Try sanding with 320 or finer... birch is hard as hell and will reward your results.

Not that I couln't learn something new... but what is up with using PVA as a finish? That's a new one on me. Curious, but I don't think I would mix it with oil.

Are you going for a blonde finish?

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Old 3rd August 2006, 10:34 PM   #3
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In most cases you shouldn't really sand plywood because
it's just a thin veneer of the quality wood on the outside.
Lightly sand with a few strokes if anything.

Please share your favourite method of finishing ply to give me some inspiration!

There are a zillion recipes for wood finishing, I've tried many.
Sometimes the simple recipe works best like applying some
stain, let dry then apply a thin coat or two of polyurethane by
spray or wipe on method.
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Old 3rd August 2006, 10:43 PM   #4
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The blotchiness is caused by the same effect as solid wood: differences in grain absorbing the colour coat to a varying degree. IME, the fix is the same as with solid wood: apply a sanding sealer as a first layer before you apply your colour/finishing layer. With birch ply, I've done sanding sealer + natural colour stain + polyurethane protective coat and was very happy with it. I use MinWax products because they are cheap at Wal-Mart.
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Old 4th August 2006, 05:17 AM   #5
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Looks familiar!

What you are probably seeing is the oil accentuating the natural characteristics of the wood. Oil is noted for this effect.
Birch can be unruly. Especialy radialy cut or "peeled" veneer as in your example.

If what you have is not appealing try a surface finish like lacquer or water white varnish. Water borne varnishes/poly's and most lacquers will do less to accentuate the wildness of the grain pattern.
Avoid finishes with high oil content or that appear amber in the can.
Most water borne varnishes fit the bill perfectly.

You could also try sanding sealer as a first coat. It has a high stearate content that fills and blocks the grain somewhat for a more even finish. Follow with lacquer as a top coat.

An oil based pigmented stain, not dye, that is nearly the same color as the darker portions of the raw wood can even the tone some too. But it will make for a darker finish.
Don't use Minwax stain, too much dye in it. Use varnish as a top coat.

A coat of very dilute blonde or bleached shellac* may be necesary before the varnish if the wood is very ill behaved.
You can try the dilute shellac before the stain too if the stain appears too uneven.

*Very dilute is like 4 to 6 parts alcohol to 1 part pre-mixed blonde or bleached shellac. Or 1-3 teaspoons of flakes in a pint of alcohol. You'll know it's right if it seems too thin at first, as though nothing is there, but it works wonders.
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Old 4th August 2006, 12:58 PM   #6
Vikash is offline Vikash  United Kingdom
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I'll pick up some sanding sealer and see how that goes.

On the pic below I've tried a few coats of pva (left for 10 mins) and then a single coat of danish oil (left overnight) followed by generous amount of aerosol applied lacquer. This looks to be one way to go (but with a better base instead of pva and proper 2pk lacquer). It looks better in the pic then in the flesh.

Click the image to open in full size.
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Old 4th August 2006, 01:10 PM   #7
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For birch, the tearing of the grain in the cutting of the veneer is a real pain. A cabinet maker's scraper does a better job of finishing than sandpaper, but I tend to cheat, and use a thin acrylic varnish then wax over the top.
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Old 4th August 2006, 01:33 PM   #8
Vikash is offline Vikash  United Kingdom
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I wouldn't trust myself with a plane. I barely trust myself with a sander. I remember when I was building my first ever speakers at uni, I used a powered planer and ripped the MDF cab to shreads. My house mates laughed. A lot.

What wax do you use pm?

I'm looking for a light overall finish but one that still shows up the natural wood veins. I'm not after a rich/dark or amber looking finish so the danish oil will probably be dropped.

A final color something like this would be ideal (or even the table the round scrap ply is sitting on in the pic a few posts up):

Click the image to open in full size.
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Old 4th August 2006, 02:11 PM   #9
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This is a cabinet scraper. It's a great tool for finishing, and once you get the hang of it, really nice to work with.

As for finishing, for I would guess for 90% of my projects, I use Mylands Antique Wax, it has a slight brown stain that really brings out the wood. Below you can see some samples, bottom is raw wood, middle is with the acrylic, and top is with a final coat of the above wax. Birch is quite difficult to get good grain figuring unless you use some sort of colour somewhere in the process.
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File Type: jpg birch copy.jpg (83.3 KB, 2448 views)
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Old 4th August 2006, 02:15 PM   #10
soongsc is offline soongsc  Taiwan
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We've tried water based filler to fill the pores, then some sanding, a few layers of primer, and one top coating. Looks clean, but without 3D look. The paint looks white in the container, but dries clear. It does not bring out veins as I would like though.
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