How to best sand / polish a de-fretted polyurethane neck

[Fretless Wonder]

Hi Gang,

I’m not new to fretless bass guitars or fretless playing but I am new to de-fretting bass necks, and I just de-fretted my first neck a few weeks ago.

I sanded down the pointed tip of a soldering iron, and then I cut a concave shape into it with a dremel stone so that it would sit flush against the frets.

I then proceeded to heat up the frets and pulled them out with one of my wife’s crafting pliers that resembles a professional fret pulling tool.

Once all the frets were out I cleaned up the channels (that don’t run all the way to either edge) and I filled them up with a two part wood filler that closely resembles and acts just like auto body filler.

I went with that over veneers because quite honestly it was a lot faster & easier with less fuss and less measuring.

After that I sanded down the neck with 360 grit sandpaper using a 12 radius block from Stewmac.

Once all of the channels were cleaned out and the neck surface was thoroughly cleaned I brushed two coats of polyurethane on, and then I finished her off with pouring the last coat on as it self-levels itself. (I wanted a really thick overall coat of poly)

No I didn’t sand between coats, and no I didn’t sand before the last coat because personally I think that’s ridiculous. The poly isn’t rock hard after the recommended 4 hour wait time between coats (of this particular poly) and the new poly that went on last will “gel” and blend right into the previous coat without the need of sanding.

Having said all of that: she looks absolutely beautiful and the gloss is so bright it hurts to look at (which is what I wanted).

I plan on letting her sit for two, possibly three weeks to really cure well before I do a final wet sand & polish, and that’s where my question is.

I’ve seen and read a lot about wet sanding & polishing after the final coat & cure, but all the verbiage I’ve seen seems to pretty much be all over the place regarding which type of paper, grit, technique, final polish, and how best to do it to keep the luster of the cured polyurethane.

What type of paper, what stage of grit (in succession), technique, and final polish would you experts that have done this before advise?


Thanks in advance for any guidance or advice.

[FretLessSince68]

Thanks for your contribution to FretlessBass.com !!!

Good info.

When doing a polyurethane polish you will not be able to preserve the sheen and gloss of the top wet coat. But you can restore it.

I assume that like me your top coat is not absolutely perfect due to dust in the air so there are some tiny bumps (dust) and possibly a pit or two.

Wet sanding and polishing is an easy process but you do need the right tools. You will be wet sanding with the finer grits available then polish using automotive polishing compounds and tools (if available).

You will need multiple grades/grits of wet sanding paper. Use the black paper that is rated for wet sanding. You can get up to about 1500 at the hardware store. I have found this is fine enough if you plan to use polishing compound. If not using polishing compound you will probably need finer grades that are available through StewMac or other suppliers.

After final wet sanding with 1500 grit transfer to polishing using automotive polishing compound.

The process WILL disturb your perfect sheen top coat of poly so accept that loss if you want to get rid of the bumps. The good news is that a good polish job will be just as beautiful as the natural top coat sheen.

Start with a fairly fine grade of wet type sand paper, no courser than 400. I would start with 600 or even finer to avoid putting excessive scratches into your poly coat. The finer the grade you start with, the less damage you do to the top coat. There is a trade off, if you have some significant bumps you will be working longer to take them down with a fine grade. If you use a course grade such as 400 grit the work will go faster but there may be scratches that require more sanding with the subsequent finer grades of wet sandpaper.

You will need a sanding block for hand sanding. I like the rubber ones. You can use radius blocks too but the moisture may damage them.

Keep the work wet by soaking the sandpaper in water. It's a good idea to soak the sandpaper ahead of time to soften it up. As you sand, frequently clean/wash the sandpaper to avoid particle buildup and other problems. Be sure to take it out of the water and clean it when you are done to preserve for your next job.

Do the work in an area than will not be damaged by water or mess. Have paper towels or rags on hand. Try to protect your instrument from water exposure. Wipe spills and drips quickly.

Start with the courser grit and progress toward very fine. If you are hand sanding the final sanding with 1500 grit should be done using circular motion. Continue until swirl marks or scratches from previous grits are gone. You may have to revert to the next courser grit if not successful, then move to the finer grit.

At this stage you will see a dull, but very smooth, surface. Now you need to finish by polishing.

If you have an orbital automotive polishing unit, some new or clean pad(s), and a selection of polishing compounds you are almost done because the work itself goes quickly. If you do not have these materials on hand I would inquire with your friends who are automotive enthusiasts if they might help you out with the final polishing.

You can polish by hand too if your elbows are in good order.

Use successive grades of polishing compound moving from coarse to fine (glaze). One pad per grade, don't mix. If using a power polisher be sure to always keep the tool moving, never linger in one spot. This can be a messy job so be prepared.

The final product should be as glossy as your natural top coat.

I hope this helps, and thanks for the great posting.

[Fretless Wonder]

No, Thank you, seriously……

Just when I was about to give up on checking to see if someone would answer my post I got the best reply & answer anybody could ask for.

Everything you said makes perfect sense. I used to paint cars and do body work a thousand years ago when I was a kid so none of the materials you mentioned are foreign to me.

I’ll follow all of your instructions to the letter, and I’ll post pictures of the finished bass when the whole thing is done. (strings & all)

This particular bass started out about 15 years ago as a Dean Edge One 4 string fretless with a very beautiful thin body & neck. (Similar to Ibanez Bass Guitars)

I played it on & off for years and always loved the rich, warm tone it gave for such a low-end bass. (low-end of course meaning price)

A few months ago I went to pull it out of the soft gig-bag (mistake number one) and low & behold the head was snapped over dangling……….and of course no one in the house fessed up to it.

Long story short – after searching for weeks I finally found a Dean Playmate fretted “lefty” neck on eBay that had the same dimensions as my broken neck, so I picked it up for $35.00 dollars.

You already know all of the rest from my previous post.

Once again, thanks for all the great advice and I promise to do a follow up for others in the future who may ever want to do something similar.

[Fretless Wonder]

Well………………………

Epic fail on the poly guys…..

I applied three coats (per the manufacturers instruction) let it sit for over two weeks in a cool dry atmosphere to really cure well, and when I went to wet sand it yesterday, it literally peeled off in layers and was still soft from top to bottom.

It was rock hard to the touch but once I hit it with wet 600 grit (and up) sand paper, it folded like a cheap suit.

I bought the poly specifically from a store that specializes in wood products and the sales rep assured me that the stuff I bought was top notch and perfect for guitar necks……………………….NOT!!!!!!

I wound up sanding it all off down to the base wood, went to Home Depot and bought a small can of Red Mahogany Minwax satin stain (no gloss or built in poly) stained the neck with two coats, and she looks beautiful.

I’m actually happier with the results than if the poly had worked.

I guess my little foray into trying to do a “Jacko” just didn’t work out.

Thanks for the tips & advice just the same, maybe I’ll take another stab at it someday in the future on another bass project and have better luck.

Ciao……….

[FretLessSince68]

Hmmm, that is a disaster. I'm wondering why it didn't adhere/cure at the wood.

A couple of ideas...

The wood of the fingerboard may have been very oily. Woods such as Rosewood.

For others interested in doing this modification it might be a good idea to seal the grain before applying polyurethane. Same goes for other oily woods.

Stripping the oil from the fingerboard using a solvent such as Naptha might help.

Another thought is that the urethane itself may have been a bad, or old, batch. When doing this job I try to use fresh product intended for coating FLOORS.

Sorry this didn't work for you.

There are other more modern materials available that might be better. Jaco used the products available at the time. Investigate what Pedulla and Roscoe use on their Diamond Coat - coated fingerboards. I also heard about a guy who has a business of coating fingerboards for fretless players with excellent results. I don't remember his name, perhaps another FretlessBass.com reader has some input.

[Fretless Wonder]

I thought about those things as well but I was extra careful “not” to use any type of cleaner that might have oil as I have seen several threads on other bass forums where people had disastrous results because there was an oil residue left on the wood.

I think it was a combination of the humidity levels where the bass was when I first applied the poly, the manner in how I applied it, combined with this particular poly (Watco Wipe-On-Poly) not being everything the salesman said it was.

I bought the correct radius block for the neck of the bass, and used first 320, and then 600 grit sand paper to prepare the neck after I filled in the frets with a two part wood filler. (that worked beautifully I have to add)

I bought those gray “sponge” style stain applicators, poured some poly into a clean container, and commenced to dip the applicator into the poly, and then I applied my first thin coat to the neck.

After four hours (per the manufacturer’s suggestion) I applied the second coat with the same applicator, but when I went to put on the last coat (after another 4 hour wait) I literally poured the poly onto the neck leaving a 0.20” thick layer

No I didn’t sand between coats

How did the poly stay on the neck without pouring over the sides?

I put painters tape all around the boarder of the neck so the poly wouldn’t spill off or out

Yes, it looked like a trough where a horse would drink water from…

Try to dry your eyes from all the laughter so you can continue reading the rest of my adventure.

Why did I make a trough and do it this way……..in my infinite wisdom, I figured thicker was better, and it would last longer once the whole job was done.

Overall I let it sit for over two weeks after it initially sat in the basement that was mildly humid for a couple of days before I moved it to a better atmospheric environment.

Once it hit the “almost three weeks” stage, I figured it was safe to sand because it was rock hard to the touch, and I couldn’t even get it to dent in with my fingernails.

I don't think that last layer of poly ever fully cured, and that's why it peeled off while I was wet sanding it, but you would’ve thought that the first two layers I applied would have held up because they were much thinner and had longer to cure.

I don’t know, I’m not a wood guy, I’m actually a metal guy that plays bass so my little experiment went down in flames.

I actually prefer the stain look, and she looks gorgeous.

When I get strings on her I’ll post some pics.

Thanks for all the help & advice, and I promise to leave this to the pros if I ever try it again……

[Rando]

I tried recently to lay down a glass sheen CA glue finish on a rosewood board that had previously been polyed. It didn't stick very well and I ended up chipping it off, damaging the rosewood a bit, having to fill in some dings, and then just today have started over with Min Wax Polyshades satin Poly in their "espresso" tint. Going with very thin coats and allowing for plenty of cure time at room temperature. It's gonna take about three coats of the Polyshades, and then satin Wipe On Poly after that several times. I did de oil the wood with Acetone, after the CA debacle.

I previously had Wipe On Poly on this neck, and took it apart to remove the marker dots, and install some side marker dots at each old fret position. (this is a de-fret). Then I got the idea to go do a CA glue glass sheen finish, which I was able to get, but the CA didn't adhere to the old wood very well. It chipped off in several spots when I removed the masking tape.

So here I go again with Poly. Up until this I had several hundred hours with DR Black Beauty Coated strings. I am going with GHS Pressurewounds this time. I think the key with poly is to go with very thin coats, and plenty of cure time in between, along with a very very light sanding between coats. Then later on, hopefully much later, you can lightly sand and lay down more poly to fill in the string wear.

Try as best you can to avoid the sideways bending of the strings and you will greatly minimize the wear marks. Every fretless will wear, even with flats. Just consider it a maintenance item to sand and touch up the finish periodically. Run as low an action as you can deal with and avoid the gorilla grip on the strings.

See my earlier "Defretting for dummies like me" piece for more information on sanding and making a sanding block to fit your neck.

Fretless is where it's at, once you get used to it.

[Fretless Wonder]

I wish you well with your latest project, and it definitely sounds like your no stranger to any of this.

The original neck that was on my bass didn’t have poly and I loved the sound.

I only did the poly thing because I figured it was a good time to try it since the replacement neck had to be de-fretted, filled in, and sanded down anyway.

I figured I’d do a “Jacko” and see what the neck sounded like with poly but alas - it wasn’t meant to be.

I’m fine with the neck just being stained without the poly, and my next task is to put the Hipshot Bridge I just bought on her.

Since the replacement neck I found only has 22 frets instead of 24 (like the original) it threw the scale off because the original bridge was positioned on the body to compliment a 24 fret neck.

I’ll have to shift the new bridge back about an inch or so to get the “nut to saddle” 34 inch scale back.

My other basses are: an ESP LTD B-104 4-string fretted bass that growls like a bear and is extremely punchy, and a Douglas Violin Beatle Bass with Labella flat wounds that has a very jazzy, upright bass tone to it.

I love fretless bass guitars for the emotions you can get out of them, they seem to come alive when they’re played opposed to fretted basses.