Well it's not that silly of a question as you might think at first. Of course we do it because we are proud of the beautiful wood that our furniture is made of in order to protect the wood. We need a finish that keeps the dirt, water and sun rays out. We also want to keep the wood waterproof or otherwise the furniture would rot and look horrible In many ways the most important thing about our varnish is that it keeps the UV rays out and believe me, it is the UV that damages the wood and the varnish. That really is the most important thing about varnish or any other finish.
OK, now we know that UV damages the wood and that the varnish has UV blockers in it, so it protects the wood and all the coats of varnish below it.
Varnish can only provide so much protection and once it has been used up, the UV will get through and start to damage the layer of varnish below, until it reaches the wood. Once the UV works on that it starts to break down and the varnish starts to break away from the wood. Of course this will allow water to get in, which speeds up the breakdown of the finish.
When this happens, the best results can be achieved when you remove all of the varnish then refinish the piece of furniture.
This is why old varnish just peels off in sheets, although the varnish itself isn't too bad.
How do we prevent this? Easy, we never let the varnish fully loose its UV protection. So the answer is simple, you need to sand back a coat or two and replace them with new varnish every five years. In my opinion, if the furniture spends lots of time outside in the sun, I would varnish it once every two years.
This will help seal any cracks before the weather deteriorates the furniture..
If you use polyurethane, you can leave it longer between coats and maybe you can. But with varnish, you are going to have to re-coat sometime and traditional varnish is much, much easier to remove and repair between times.
It is also worth remembering that you can always use a traditional varnish on top of a modern polyurethane but not the other way around. I often I like to apply a base of hard polyurethane varnish and then top it off with traditional varnish.
The important thing is to always keep your varnish topped up and regularly sanded down and apply a new coat or two of varnish to keep your UV protection up. If you do do this, then the varnish will keep out the sun for a while longer,
but sooner or later it will start to break down.
Now you say to yourself, if I put a couple of coats of varnish on every year, then in a
few years it will have 3 tons of varnish.
Well I know it seems like that would happen. But it doesn’t work like that.
As the UV breaks down the varnish, it oxidizes and thins and it is easy enough to sand off
a couple of coats of varnish before you put the new varnish on. You can go on building up
varnish, and as long as you sand between, it just gets flatter and better looking every
year. There will come a time, when you need to take it all off and start again, at which
time you will be very thankful if you decided to use traditional rather than polyurethane
varnish.
OK so you have prepared your wood or varnish and now you want to get down to getting the
varnish out of the can and onto the wood.
Ready to apply your varnish? Some choices for applying varnish.
If you are starting on bare wood, the first few coats will need quite a bit of
sanding before the grain of the wood is fully covered by the varnish, you
will most probably need to use something like 240grit sandpaper to do this.
But once you
have gotten the base coats nice and flat it becomes easier to build up lots of layers in
quite a short time.
Is it pretty yet?
With a little luck, your varnish should by now look just glorious, with a deep golden color and
just like glass. If it's just about perfect then that's probably because you have been working in
a small, dust free, centrally heated workshop, rather than an open garage with the wind
whistling through and depositing dust or pollen in your varnish.
Why not just polish it?
You can polish some varnishes only once they have really gone HARD.
So it follows that the hard poly and mono urethanes are much easier than the traditional
varnishes and I certainly would not try to polish one of the oil finishes.
How to polish your varnish?
First you allow the varnish to really harden! To be safe this means a waiting
for a couple of
weeks. Then you get some 1000 or 1200 grit wet and dry sand paper and using lots of water with a
little detergent in it, you rub down the varnish. If you find that the paper is blocking
up with varnish, then the varnish is way too soft, and you need to stop. All you are
trying to do is to flatten any dust etc, once you have done this, it should be FLAT and
just a little silky, but not matt, if it's matt you have gone too far and will need to
rough it up with some 180 grit and put another coat on.
Then make a quick visit to your local auto-shop and get some auto rubbing compound..
Using the rubbing compound, in small areas, work slowly rubbing it out.
By the time you finish
with that it should be both flat, and totally sparkling, just as if you sprayed it.
I have to say, the thing about polishing is that it won't rescue bad varnishing, and to be
honest, the better the varnishing is to start with, the bigger difference it will make.
If you have a good base that has been spoiled by a less than perfect topcoat, you might
get away with it.
Furniture has been varnished in one way or another for hundreds of years and yet despite
all that time and practice, it appears that there is still no agreement about the
best kind to use. Every year there seems to be some newer or better varnish available.
Despite that, some old boys are still varnishing furniture with finishes that look like
glass using just the most basic and old-fashioned varnishes.
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