Finish questions: Teak Oil over Sanding Sealer?

[ack1961]

Hello,

I posted this question in the Luthier's section on TB, but I also wanted to see if anyone at The Outpost had any opinions...

I am building my first bass guitar and I am a bit stumped when it comes to the finishing aspect. Not especially craft-worthy, I have done quite a bit of research which has allowed me to get this far. Please overlook my lack of tech-speak when it comes to this craft. I'm getting there.

In a nutshell, I am shaping and finishing a body out of a 1.75 inch thick 2-piece slab of Alder - a nice cheap introduction to bass building - I wanted to keep the finish natural to expose the grain, knots and other characteristics of the wood. I intend to use MinWax Clear Gloss Polyurethane spray to finish.

I've read many articles and I own a few books on building, but I'm constantly seeing unbelievable results from people who have used their own slants/interpretations on proven finishing techniques...which leads me to a couple of questions.

First, a synopsis of what I've done so far:

After shaping and routing, I started sanding. Using a block, I started with 80, then 120, then 150, then 220. I then put 220 on an orbital sander and continued. I got the surface very even and smooth, where you couldn't really feel the grain.

I then put on a light coat of Sanding Sealer and let it dry - The top and back looked beautiful, the sides got darker than I hoped - the body is a Telecaster guitar slab shape (no body/comfort contours). I lightly sanded the whole body down with 220, and it got substantially lighter.

I put a second light coat of Sanding Sealer on and the top/back looked great. The sides are still too dark for me, so much so, that I went back to 100 grit and removed the SS and went through 120/150/220 to get the sides back in good shape.

All along, I kept small samples of Alder off to the sides and experimented with them. One of the finishes that I really like on the sample is Teak Oil. It just glows the most beautiful amber, and I'd like to use it.

Finally, my questions:
1. Will the Teak Oil co-exist on top of the 2nd sanded coat of SS?
2. Is it "safe" to use Teak Oil on the sides now that I've sanded them down (after 2 coats of SS)?
3. Spray-on Poly OK on top of Teak Oil?

I've posted a few pictures of the build here:
http://bassoutpost.com/index.php?topic=4322.0

I'll appreciate any constructive assistance that is offered.

Steve

[drbassman]

The best place to research finishing the the Reranch refinishing forum at:  http://www.reranch.com/reranch/

To the best of my knowledge:

1. Will the Teak Oil co-exist on top of the 2nd sanded coat of SS? OILS DO NOT TYPICALLY GO WELL OVER S&S COATS.  OILS UNDER NITRO S&S WILL WORK, BUT I DON'T BELIEVE THE OTHER WAY AROUND.  ALL WOOD FINISHING OILS NEED TO SOAK INTO THE GRAIN AND S&S WOULD PREVENT THAT.

2. Is it "safe" to use Teak Oil on the sides now that I've sanded them down (after 2 coats of SS)?  IF IT'S RAW WOOD, YES IT'S SAFE.

3. Spray-on Poly OK on top of Teak Oil?  I DON'T THINK SO.  AGAIN, MOST FINISHING OILS ARE COMPATIBLE WITH NITRO BASED FINISHES, BUT NOT POLY.  ONCE YOU GO DOWN THAT POLY ROAD, YOU ARE PRETTY MUCH STUCK WITH USING POLY-BASED PRODUCTS.

In the end, it's always best to test on scraps of wood.  Hope this helps!

[Dave W]

If it's actually a pure oil, then the answer is no. The problem is that wood finish manufacturers often misrepresent what they market as oil finishes. I've never seen a teak oil that's actually a genuine oil finish. Every one I've seen is either a varnish (often a long oil varnish for outdoor use) or a varnish/oil mixture. Trying to get a straight answer out of many manufacturers is difficult but if it says it cleans up with mineral spirits or paint thinner then it's not a true oil.

[ack1961]

If it's actually a pure oil, then the answer is no. The problem is that wood finish manufacturers often misrepresent what they market as oil finishes. I've never seen a teak oil that's actually a genuine oil finish. Every one I've seen is either a varnish (often a long oil varnish for outdoor use) or a varnish/oil mixture. Trying to get a straight answer out of many manufacturers is difficult but if it says it cleans up with mineral spirits or paint thinner then it's not a true oil.

Thanks for the response.  Cleanup does say Mineral Spirits or Thinner, so I guess it's not a true oil.  Anyway, yesterday (it turns out that it went against some people's advice), I put a coat of Teak Oil on and let it sit for an hour, then rubbed it in (what's the worst thing that could happen? A ruined finish? Sandpaper cures those kind of mistakes).

Anyway, it has a beautiful, silky golden glow, and I'm going to wait about 72 hours then spray on some MinWax Clear Gloss Poly.
What I'm really happy about is the consistency between the front/back and sides.  The sides were so much darker after the Sealer application, I ended up sanding the sides down quite a bit.  Here's some pictures in bad lighting (the Sun's just coming up)



Thanks for the help.

[ack1961]

The best place to research finishing the the Reranch refinishing forum at:  http://www.reranch.com/reranch/

To the best of my knowledge:

1. Will the Teak Oil co-exist on top of the 2nd sanded coat of SS? OILS DO NOT TYPICALLY GO WELL OVER S&S COATS.  OILS UNDER NITRO S&S WILL WORK, BUT I DON'T BELIEVE THE OTHER WAY AROUND.  ALL WOOD FINISHING OILS NEED TO SOAK INTO THE GRAIN AND S&S WOULD PREVENT THAT.

2. Is it "safe" to use Teak Oil on the sides now that I've sanded them down (after 2 coats of SS)?  IF IT'S RAW WOOD, YES IT'S SAFE.

3. Spray-on Poly OK on top of Teak Oil?  I DON'T THINK SO.  AGAIN, MOST FINISHING OILS ARE COMPATIBLE WITH NITRO BASED FINISHES, BUT NOT POLY.  ONCE YOU GO DOWN THAT POLY ROAD, YOU ARE PRETTY MUCH STUCK WITH USING POLY-BASED PRODUCTS.

In the end, it's always best to test on scraps of wood.  Hope this helps!

Thanks for the help and the links.  The sides turned out great - I'm really glad that I didn't settle for the way they looked and then re-sanded them.
The body finishing has been the most frustrating part of this build.

[dadagoboi]

I don't understand using teak oil over sanding sealer or under poly.  What exactly is it and what is it supposed to do?  I'm pretty sure it's little more than a wiping polyurethane since it cleans up with mineral spirits.  Finishing techniques have gotten way beyond esoteric with major marketing to sell the same stuff under different names.  Teak Oil = Snake Oil IMHO.

For info on wood finishing with rubbing oils, google 'French Polish', a many hundred year old finishing technique that is basically a cheesecloth ball soaked in shellac and rubbed into scraped wood until it shines like a mirror.

[drbassman]

I don't expect your poly top coat to stick to the oil.  If it does, I will be totally surprised.

[Pilgrim]

I don't expect your poly top coat to stick to the oil.  If it does, I will be totally surprised.

I was wondering about the same thing.  Might Tru-Oil be a workable choice for the top coat?  It's another of those "mixed bag" finishes, but it  dries with a hard finish.

[dadagoboi]

Minwax says:

"a topcoat such as Minwax® Helmsman® Spar Urethane can be applied over Minwax® Teak Oil. Although we recommend that Minwax® Teak Oil be reapplied to dry, worn out wood, a topcoat such as Minwax® Helmsman® Spar Urethane will offer additional protection. Wait a minimum of 72 hours after applying Minwax® Teak Oil before applying additional topcoats."

Polyurethans is an oil finish, you reduce/clean it up w/mineral spirits.  Watco, Danish, Tung, etc oils are basically the same as teak oil.

Minwax also says to use teak oil on bare wood or wood that has all the old finish removed.

[ack1961]

I'll start reading up on Tru-Oil and see if that's a viable top-coat for my teak oiled project.
Thanks for all the research, comments and ideas.

[Dave W]

I'm going to disagree with some of the comments above.

Your teak oil finish is definitely not a real oil finish. It's either a varnish (polyurethane or another resin) or an oil-varnish blend. If it's a varnish, you should have no problem with the topcoat.

All varnishes have some kind of oil in the formula, but it's combined chemically with a resin and other ingredients to make it a varnish. So a true varnish has no oil in the finished product. Long oil varnishes have more oil in the formula which makes the finished product more flexible, mostly these are intended for outdoor use. Short oil varnishes are harder and more wear resistant but don't hold up to weather conditions.

Tru-Oil is not an oil no matter what evasions the manufacturer uses. It's a wiping varnish. The "modified oil" in the MSDS is a buzzword for alkyd resin. It builds, like all resin finishes.

More later.

[drbassman]

I'm going to disagree with some of the comments above.

Your teak oil finish is definitely not a real oil finish. It's either a varnish (polyurethane or another resin) or an oil-varnish blend. If it's a varnish, you should have no problem with the topcoat.

All varnishes have some kind of oil in the formula, but it's combined chemically with a resin and other ingredients to make it a varnish. So a true varnish has no oil in the finished product. Long oil varnishes have more oil in the formula which makes the finished product more flexible, mostly these are intended for outdoor use. Short oil varnishes are harder and more wear resistant but don't hold up to weather conditions.

Tru-Oil is not an oil no matter what evasions the manufacturer uses. It's a wiping varnish. The "modified oil" in the MSDS is a buzzword for alkyd resin. It builds, like all resin finishes.

More later.

Dave's knowledge trumps my basic understanding of things.  The compatibility between "varnish" (A non-oil based product) and poly is new to me.  I'm looking forward to learning more about this phenomenon............  

[dadagoboi]

Thanks for chemistry lesson Dave!

[Pilgrim]

Dave's knowledge trumps my basic understanding of things.  The compatibility between "varnish" (A non-oil based product) and poly is new to me.  I'm looking forward to learning more about this phenomenon............  

And it trumps mine as well!!

I feel like Boon in Animal House....

"You better listen to him - he's in pre-med!"

[ack1961]

and just to fully clarify, here's the process/layers (top-to-bottom)

Watco Teak Oil
Sanding: 220/400 (Sanded sides 120/150/220/400)
MinWax Sanding Sealer
Sanding: 220
MinWax Sanding Sealer
Sanding: 80/120/150/220
Bare/new Alder (1.75 inches thick)