Tung Oil Overlap / Light/Dark Streaks

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Forum topic by Tim & Candy Hicks posted 09-12-2009 12:41 AM 5096 views 0 times favorited 4 replies Add to Favorites Watch
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Tim & Candy Hicks

325 posts in 3131 days

09-12-2009 12:41 AM

Topic tags/keywords: question finishing

So this is the problem. We have applied our first coat of tung oil and noticed that there is overlap and some lighter/darker streaks… will these blend together as we add mor oil? How do we fix it

We used a high lustre polymerized tung oil and it is applied directly to the wood, there are no sealers or stains



4 replies so far

View GMman's profile


3902 posts in 3119 days

#1 posted 09-12-2009 01:01 AM

Wood Preparation:
The surfaces to be finished should be free of lint, dirt, grease, wax, oil, old paint or finish. For new wood, the surface should be sanded to a 220 grit finish. Avoid using higher grits as they close the pores, minimizing penetration of the Polymerized Tung Oil Sealer. Vacuum and tack the surface to remove any dust .

Finishing Conditions:
Ideal conditions are a temperature range of 55-75° F with humidity less than 65%. Whenever you finish in conditions out of these recommended ranges you may experience difficulty in applying the finish and you will need to allow for longer curing times. Reapplying finish before the previous coat is adequately cured causes STREAKING and FLASHING of the finish. This is evidenced by dull areas in the finish where moisture is trapped. Avoiding streaking and flashing in the finish is a function of adequate curing time. Curing time is a function of finishing conditions, thickness of coat applied, lustre being used, number of coats previously applied.

Sutherland Welles Ltd® Polymerized Tung Oil is formulated to be used as a wiping finish, that is applied, allowed to penetrate and then thoroughly removed from the surface. The amount of driers in the oil are insufficient to facilitate adequate curing if the oil is used as a surface finish, that is brushed on, left on and allowed to cure.

Our Polymerized Tung Oil’s highest performance is with solid wood, not veneers. Veneers are best finished using a combination Polymerized Tung Oil/ Resin finish. Sutherland Welles Ltd® offers Wiping Varnish and Murdoch’s line as a more successful finish for veneer.

Application of Polymerized Tung Oil Sealer:
After properly preparing the wood surface, apply the first coat of Sealer liberally with a natural bristle brush. It is not uncommon for most of this coat to be absorbed into the wood with a minimal amount left on the surface. After 10-15 minutes, wipe the surface completely using a clean rag or cheesecloth. Allow the first coat to cure approximately 6-8 hours. The sealing process tends to raise the grain of the wood, although less with a wiping finish. If the surface feels rough after the first coat has completely dried, lightly sand the surface using a 220 grit sandpaper. Vacuum and tack the surface prior to applying the second coat of sealer. The second coat is applied using the same technique, but using less Sealer. Completely cover the surface with Polymerized Tung Oil Sealer and allow the sealer to penetrate approximately 10 minutes. Completely wipe the surface dry with a clean soft rag or cheesecloth. Allow the second coat to cure 6-8 hours. If the surface isn’t smooth enough to your preference, sand with 320/400 grit sandpaper or #0000 steel wool prior to applying the finish coats. Remember to vacuum and dust the surface prior to re-coating.

Application of Low, Medium or High Lustre Polymerized Tung Oil
Using a natural bristle brush or a clean rag, apply the finish coats thinly. Allow 10-15 minutes for the Polymerized Tung Oil to penetrate and then using a clean rag or cheesecloth, wipe the remaining Polymerized Tung Oil off using a circular motion. Keep changing the area of the rag to a dry spot to pick up all traces of the Polymerized Tung Oil. Your final wipe should be in the direction of the grain of the wood. Allow 12-24 hours for this coat to both dry and cure. Successive coats are applied using the technique described above. If the surface should tack-up before you wipe it off, simply apply more Polymerized Tung Oil and wipe off immediately and thoroughly.

Cure Test: To avoid STREAKING AND FLASHING in the finish, perform the cure test prior to applying a coat of finish. Streaking and flashing are the appearance of dull spots in the finish. This occurs when moisture is trapped in the layers of finish due to insufficient curing time. Push your finger tips against the grain of the wood over the various parts of the surface to be re-coated. If they glide easily over the surface – you are ready to apply your next coat. If there is any “grab” or friction felt, you will need to wait longer for this coat to cure. Repeat the cure test every two-four hours until your fingers slip easily across the surface.

Coverage:Sealer- 150-200 sq.ft/quart or 600-800sq.ft./gallon. Low, Medium and High Lustre- 1000sq.ft./gallon (after two coats Sealer). Available in quarts, gallons,pails.

Waxing (Optional)
After the surface is completely cured, the finish may be waxed using a carnauba paste wax. The technique we recommend is to use a piece of #0000 steel wool dipped in a small amount of turpentine and then into the wax can. A small amount of paste wax goes a long way using this technique. We buff before the wax is completely dry with a clean soft rag. Make sure you avoid loading the wax into crevices as it will dry and become obvious. Carnauba paste wax is available in white, orange and antique brown color.
Maintenance of a Polymerized Tung Oil Finish

Periodic maintenance – use only Sutherland Welles Ltd.® Dust and Tacking Oil™ according to directions on the label. Formulated with a high quality mineral oil and our low toxic solvent, Di-citrusol™, the product is perfect for removing everyday dust from furniture, cabinet etc. Perfect to prep surfaces prior to using any surface coating such as our Murdoch’s Table Top™ or our Wiping Varnish.

Yearly maintenance – use Sutherland Welles Ltd.® Wood Care™ according to directions on the label. This product is formulated with our Polymerized Tung Oil and our low toxic solvent, Di-citrusol™. Wood Care™ is perfect for any project finished with any of our products. Wood Care™ enhances the patina while protecting the wood.

Resurfacing of a Polymerized Tung Oil Finish

There are three steps to resurfacing a Polymerized Tung Oil finish; clean, sand, re-coat. Over time, any wood finish will need rejuvenation. Grime, dust, environmental exposure all take their toll on a finish.

The first step is to clean the surface using Sutherland Welles Ltd.â Cleaner according to the directions on the label. If the surface has been waxed, a penetrating finish will dissolve enough of the wax to maintain the integrity of the Loc-Lamin® System. Once the surface is clean, lightly sand the surface with a 400/600 grit sandpaper. The final step is to use Sutherland Welles Ltd.â Polymerized Tung Oil in either Low or Medium Lustre. Apply a thin coat with a clean soft rag or natural bristle brush, allow five minutes for it to penetrate and then wipe the surface completely removing all the Polymerized Tung Oil from the surface. Allow the surface to cure twelve-twenty four hours before using.

View GMman's profile


3902 posts in 3119 days

#2 posted 09-12-2009 02:58 AM

I have done more searching and it could be you wood or your sanding doing that.

View Mark A. DeCou's profile

Mark A. DeCou

2008 posts in 3827 days

#3 posted 09-12-2009 03:59 AM

What he said.

I’m thinking that the problem is in the application process. Sanding might have something to do with it, but I’m going to guess not.

I think a lot of people excessively sand, which is basically just burnishing off the end of the pores, slowing the flow of finish deeper into the wood surface. I used to sand to 320 before I knew better, but now stop at 220, but have even stopped at times at 180. For smoothness that we are all after, I generally use the wood finish to achieve that instead of a burnished wood surface.

To use Tung Oil, I saturate fully for about 30 minutes keeping it wet where it soaks in, and then wipe off excess.

I had a similar “line” problem one time with a walnut wood that I sanded and couldn’t wait to see how the burl would look with boiled linseed oil on it, so I wiped some oil on it. I also don’t use boiled linseed any longer.

Several months later I finished the project, and never could get rid of that line where I had wiped the boiled linseed oil before. A mistake I haven’t repeated.

Since then, If I want a depth to the wood like oil provides, I use Danish Oil (Deft Oil is my favorite) and saturate a full coat, let sit about 30 minutes and wipe off excess before it gets tacky. I like the depth and color of oil finish, but prefer to spray lacquer on top of it once the oil has dried for several days, as I like the smoother thicker finish that lacquer provides as well as the ease of repair of scratches. Lacquer gives more water protection than oil. If I need more water protection than that, I’ll put a coat of Poly over the laquer after it has cured completely.

To be honest, I think you are stuck with that line in the finish without going back and sanding it all the way out.

My only easy help would be to saturate with oil again and hope that it blends out a little more with another coat. If it was me, I’d resand it, and start over. Those blemishes in our work can out live the woodworker, and one day all we’ll have is our reputation preserved in the work we leave behind.

I’m not a fan of Tung Oil, but this problem you have isn’t the reason, there are other reasons for that opinion. Of Course, I don’t like Poly either, so I’m the odd man out in today’s world of woodworking and the wipe on poly finish.


-- Mark DeCou - American Contemporary Craft Artisan -

View CharlieM1958's profile


16229 posts in 3640 days

#4 posted 09-12-2009 04:44 AM

I just used BLO for the first time myself, and it seems to be much thicker than Danish oil (my standby). I found I really had to wipe it on thick in order to get even saturation, then come back after 10-15 minutes and wipe off the excess.

I’d try another coat and see what happens.

-- Charlie M. "Woodworking - patience = firewood"

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