View Single Post
  #6   Report Post  
Posted to rec.woodworking
dadiOH dadiOH is offline
external usenet poster
 
Posts: 833
Default Where does varnish go?

riverman wrote:
A few months ago, I refinished an old Teak picnic table I picked up
for a bargain. The previous owners had put all sorts of finishing
agents on it, and it looked pretty splotchy and bad. So I got a
vibrating sander and took it down to the bare wood.

I know that teak weathers out to a nice silver patina, but I really
prefer that golden 'hardwood floor' look of varnished wood, so I
got a quart of marine varnish and did some internet research.

Most of the sites I found were about refinishing boat decks, and
they mentioned things like putting on 10 or 12 coats, and how even
that required refinishing every few years. That seemed excessive to
me, so I figured it had something to do with the rigors of salt
water and spray, and probably wouldn't affect my table on the back
deck.

So I put one coat on the tabletop, which made a huge improvement (of
course), and then a second coat, which made a bit more of an
improvement. But the third coat barely made any change at all, so I
stopped after three coats.

For about six or eight weeks, it looked great and all the
neighborhood wives oohed and ahhed, but then little 'bare spots'
started showing up. Over time, they grew and increased until now
when about 20% of the table has exposed patches that are showing
that silver teak patina instead of the golden brown finish. So
today I had to restrip the table and start over.

My question: where does the varnish go? Why does something require
10-12 coats to last? I surmise that it might be one of these things:
a) varnish actually evaporates over time
b) the wood soaks up the varnish from below
c) its so thin that each coat doesn't really cover the wood
adequately, so you need a lot of coats to get a good protective
layer d) varnish breaks down in sunlight and decomposes


It's called "weathering". And yes, it is primarily the result of
sunlight...no sun no (or little) weathering. I made a teak dash board
for my car in 1992, varnished it and have done nothing since. Still
pristine.
_______________

Can anyone tell me more about this? Is it acceptable to just keep
adding layers over the top before the bare spots show up?


That's the normal method. You need to sand before applying new to
remove the oxidized layer.


--

dadiOH
____________________________

dadiOH's dandies v3.06...
....a help file of info about MP3s, recording from
LP/cassette and tips & tricks on this and that.
Get it at http://mysite.verizon.net/xico