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Tung oil curing time

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Charles Bjorgen

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Sep 30, 2001, 11:18:14 AM9/30/01
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I'm completing a natural edged bowl in cherry that I intend to give to
my son and his wife as a five-year anniversary gift (five years is
"Wood"). So far, I applied several coats of a 50-50 mixture of tung oil
and turpentine, the last coat about 10 days ago. I'd also like to then
use the Beall buffing system to finally polish this project. Seems I
heard something about how long tung oil should cure, something like 30
days. Any thoughts based on your experiences?

Ken Bullock

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Sep 30, 2001, 1:51:36 PM9/30/01
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I use Minwax tung oil on all my turningings. Two Coats ussually. After the
second coat, I buff with the Beall Buffing system, Ussually about 6 to 24
hours after applying last coat of tung oil.... It works for me....
Cheers......

--
http://www.oneofakindwoodturnings.com
MY PROJECT BOOK and several E-Books available for download on my web site.

Ken Bullock (Woodturner)

"Charles Bjorgen" <cbjo...@citilink.com> wrote in message
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Lyn J. Mangiameli

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Sep 30, 2001, 5:46:35 PM9/30/01
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Charles,
In my experience, it mostly depends on how thick a layer of oil was
applied, and to what extent the underlying layers have fully cured. Very
thin layers can cure in a fairly short while, 6-24 hours, but thicker
layers can take weeks to months. You should always be wiping off excess
oil so that you have only applied a very thin coat (which is also why it
is so hard to build a finish using pure oils), that will allow maximum
opportunity for polymerization with the oxygen in the air. However, we
some times end up with thicker coats than we should. In such
circumstances, polymerization throughout the thickness of the finish is
very slow (speeded up somewhat if you use a partially prepolymerized tung
oil such as sold by Lee Valley). Basically, if the piece feels at all
tacky, it has not yet fully cured. If it has taken several days to feel
smooth and without any hint of tackiness, it is wise to wait at least one
more day before buffing.

Keep in mind that if you buff with the brown Tripoli compond, you need to
have very good penetration of the wood or a bit of a thickness of finish
built up before buffing, otherwise the abrasive action of the Tripoli can
cut right through your finish. If you already have a fairly good surface,
but it is thin, it is sometimes best to just start with White Diamond, or
even just go straight to the wax. That said, caranauba buffed over
polymerized tung oil is one of my favorite finishes.

I'm no finish expert, so just take this as one recreational turner's
understanding of things,

Lyn

e

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Sep 30, 2001, 7:30:16 PM9/30/01
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vell.... another element to add is how dry the bowl is when the first 50/50
coat was applied.

i have experienced a white-haze developing after several coats and several
weeks ... i believe this is the result of moisture.

e

"Charles Bjorgen" <cbjo...@citilink.com> wrote in message
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Charles Bjorgen

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Oct 1, 2001, 10:01:04 AM10/1/01
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One thing I failed to mention in my original question is that I used
pure tung oil rather than any of the proprietory tung oil products that
may contain additional driers or urethanes. And after that original
posting I realized that Steve Tiedman would naturally refer me to Bob
Flexner's finishing book, which he did via email. According to Flexner's
treatise on tung oil, it may not have been my best choice, but that's
what I now have. I'll wait at least another week before doing any
buffing. I can still smell the oil but the turp odor is gone.

Good points on the buffing phase though. I hadn't thought about that and
will proceed with caution, probably on a practice piece. I still have
two months before giving the gift so I can redo if necessary.

dst...@ix.netcom.com

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Sep 30, 2001, 1:26:45 PM9/30/01
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It depends on if you're really using PURE tung oil.
Most of the "tung oils" on the market really aren't. They're a wiping
varnish mixture, i.e. Minwax & Formy's Tung Oil.
If you're using a true pure tung oil it should cure to the touch in 1
to 3 days with complete cure in 30.

Dave Stacy
www.davestacy.com

Don Evans

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Oct 1, 2001, 11:02:37 AM10/1/01
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Lyn or anyone:

I'm curious, why would anyone buff with Tripoli? Seems if white diamond isn't
abrasive enough then the bowl needs more sanding.
I've seen it done for the purposes of putting reddish highlights in the grain,
which I think is ugly, but other than that I cannot see why.
I would use Colgate before Tripoli. Teach me something new here.

Don

Lyn J. Mangiameli

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Oct 1, 2001, 2:40:14 PM10/1/01
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Don,

I'm no expert on buffing, someone like Donald Watland can probably speak much
more definitively. That said, here's my sense of things based on using both the
Beall Buffing System and the eeeUbeaut cream which contains Tripoli:

1. Agressive buffing with Tripoli can cut through almost any finish. For that
matter, agressive buffing with an unloaded cloth wheel can heat up and ruin a
shellac finish all by itself.
2. Tripoli, being brown, can load into pores and flaws in the wood surface. This
can leave a visually desirable or deletirous effect, depending on the wood and
your tastes. Followup buffing with White Diamond will often clear this out of the
pores.
3. Tripoli, being an abrasive somewhere above 800 grit and perhaps up to 2400
grit can provide a desired smoothing effect.
a. Grits in this range are appropriate for judicious leveling finishes
b. Grits in this range can greatly smooth and add luster to the finish of
very hard, dense, fine-grained woods (as well as many metals for that matter.)
c. Tripoli in its usual honing bar form is much cheaper than comparable
sandpapers
d. Tripoli buffed on does not result suffer from the problems sandpaper has
with rapid loading
e. Tripoli on shaped buffers can often follow and enter into contours that
sandpaper would be hard to conform to
4. It is not unrealistic to use Tripoli prior to applying many finishes on some
woods. It will prepare the surface and if needed, it and it's wax can be removed
with mineral spirits. Depending on wood, personal tastes, and final finish, the
Tripoli can even be used to fill fine pores prior to finishing.

Personally, I love using eeeUbeaut creme for very small turnings, usually
followed with Shellawax. For larger work, I sometimes buff with Tripoli before
finishing with oil, but usually not after, settling then for just WD and
Caranauba. However, I will use the Tripoli to cut the sheen of some lacquer or
shellac finishes, and to smooth some shellac finishes. I'm starting to experiment
using water based poly with some high tannin woods that respond well to the
waterbase. Tripoli buffing seems to be quite effective in making this finish more
appealing to my eye, but at this point I'm still just experiementing.

Again, just my thoughts and experiences. There are surely others who know these
things better than I.

Lyn

Steve Tiedman

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Oct 1, 2001, 8:24:02 PM10/1/01
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Chuck,

Yeah, Bob can be tough on pure oils used for finishing. For cabinet work, I
agree fully with him. But his book really does not address the turner
specifically, more general wood finishing. I love pure tung oil for many
woodturnings. On a lot of things, I don't want a plastic buildup of resin, I
only want to enhance the look of the grain and leave the natural wood
surface, and that's what a few (3 or more) coats of pure tung oil will offer.

Grab that can of wiping varnish (Minwax tung oil finish, etc.) and mix a
small batch 50/50 with the pure tung oil and give the bowl a top coat or
two. More oil won't hurt the finish that's there, and the varnish component
will give a bit of a surface build good for buffing.

Oh, the fun of it all! Sometimes I feel like a kid, nay, mad scientist, with
one of those junior chemistry sets. (Insert evil laugh here!)

Give me a call for any other insight. If you would like, I've got a brand
new can of McKlosky's Man-O-War varnish I was going to mix up into a home
brew. A mix of this, your tung oil, and some of that turpentine would make a
nice wiping finish. Care to mix some up? (For the rest of you, Chuck and I
are about a mile and a half away from each other.)

Steve.
--
Steve Tiedman
s...@mninter.net
Minnesota, USA
------------------

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