Build#2 GPB-4 Fretless

[FaustoB]

...my journey building fretless basses continue.
Today I have ordered a GPB-4, and I have two fretless necks coming, one rosewood and one maple. The idea is to use rosewood for this build, and maple for something else, but I will decide when I see the fretboards.

I would like to keep this build simple. I have some ebony Timbermate hanging around, and some Tru Oil that would like to use.
I haven't seen the kit yet, not sure how the grain looks like, but at the moment the idea is to use the ebony Timbermate to reveal the grain and finish with TO.

Based on my research, my understanding is that I should sand the body to 220, apply TM diluted with a bit of warm water, let dry and sand again with 220.
Then apply TO and gradually sand to 400.

Is this the way to go? The sanding stages is still la bit confusing to me.

Alternatively I could consider a natural stain, colourless, to reveal the grain (instead of TM) and then TO but I am still not 100% clear about the sanding steps.

Thank you in advance for looking into this!

[Trevor Davies]

Hi FaustoB,

"Based on my research, my understanding is that I should sand the body to 220, apply TM diluted with a bit of warm water, let dry and sand again with 220."

This sounds good.

"Then apply TO and gradually sand to 400".

I would sand even higher, I use 600 to 1200. Others may not agree here.

"Alternatively I could consider a natural stain, colourless, to reveal the grain (instead of TM) and then TO but I am still not 100% clear about the sanding steps."

Or use a dark ebony timbermate to highlight and fill the grain, then a natural stain etc. This is what I did with my TLA-1 which has an ash body.

Lots of choices!

[McCreed]

Well that didn't take you long to move on to your second build!

As for finishing with Tru Oil, you will find many differing methods but just as many similarities. The good thing about Tru Oil is it's very user-friendly and forgiving no matter what your process. I'm not saying it can't stuffed up, but you'd almost have to try.

The main reason for grain filling with Timbermate is create a flat level surface to achieve a smooth finish*. The colour of the filler is personal choice as to how much contrast you want between the grain and timber between the grain.

Further to the application method of the Tru Oil, I don't sand until I start to develop definite sheen. For me, this usually at least 8 coats in. I also don't sand between each coat unless I need to fix a significant defect like a bad stroke mark or bit of debris.
IMO, the oil goes on so thin when hand-applying, that sanding every coat can remove a significant amount of what was just put on and it will take ages to build up. Sort of chasing your tail.

*edit to add:
If you want a more "rustic" look and not aiming for a glass smooth finish, you don't need to be too fastidious about how flat the grain filling is. You can just use the darker filler for contrasting the grain more than levelling it.

[FaustoB]

Thank you so much Trevor and McCreed!
The steps and options are much clearer now. I appreciate your help, sharing your knowledge and experience.
Trevor, neat work on your TLA-1! I'm following.

[Simon Barden]

If you aren't staining the body, then sanding to higher grits above P240 shouldn't be an issue, though I'd see it as a bit of a waste of effort as you'll need to sand the TO flat if you want a gloss finish as it won't go on smoothly, regardless of how smooth the bass finish is. But it won't harm it.

What you do want to do is get the body flat before applying true oil (and even the Timbermate), which is different to getting the surface 'smooth'. The surface can be undulating but smooth as it's been finished with up to P2500 grit paper, but it won't look as good as one that's been sanded nice and flat to P240, and that has no bumps and dips. Having it properly flat also makes it easier to apply the TO evenly, and you'll reduce the risk of sanding through in an effort to get the surface flat, as there won't be any dips due to the surface that mean you need to keep sanding down the TO until those dips no longer exist, and risk sanding through the TO on the bumps.

It does help to do a very light mist spray with a coloured aerosol paint before sanding the body flat (before any grain gilling), just enough so that you can see the paint remaining in the dips when you sand the surface (I use P120 stuck onto a flat plank for this initial levelling sand). You'll sand all the paint off, so it won't affect the look. It also helps to show up any deep sanding marks on the edges.

[FaustoB]

thank you Simon for the detailed response! I appreciate it!

[FaustoB]

Ok, ash body and rosewood neck arrived, maple neck still in transit. Some questions and some updates.

QUESTIONS:
Q#1 it appears that there's a glue spot on the side of the fretboard, and some excess glue next to the plastic nut, towards the machine heads.
How do I get rid of the glue spot on the side of the fretboard? (assuming that it is a glue spot...) just sanding?
Same thing for the glue excess on the fretboard, sanding? I am swapping the plastic nut for a bone nut on this neck, so that whole thing has to go very soon.
Photos below.






Q#2
I am totally new to ash bodies, I am doing some testing inside the pickup cavity since it will be covered by copper tape anyway.
How do I made the grain to appear more even? as you can see from the photo below, the grain filler looks "interrupted" here and there, especially on the darker options.

I have sanded to 220 (sanding #1), and then applied some diluted Timbermate (TM) filler.
My tests from left to right are:
Ebony TM.
Ebony TM plus some mixed red and yellow acrylic paint.
Just Tru Oli (TO).
White TM plus a pinch of mixed red and yellow acrylic paint (probably my favourite but I think it'll depend on if I use rosewood or maple neck, TBA).

Then I sanded again 220 (sanding #2) and applied 2x coats of TO on every sample.

Should I have re applied some filler again after that second sanding? and then sand again (#3) and then go with TO? or keep applying TM and sand until the desired grain fill is reached?
Photo below



UPDATES
The ash body and rosewood neck look great and I am happy with them.
I have started some sanding since I am still awaiting on the maple neck and a high mass bridge.
This ash body was a lot of work to sand!
On the side of the body, almost around the entire body, there where some scratches, I'd imagine from when the body was cut.
The scratches are going away with some 180 sanding as you can see from the photo below.
I tried sanding with some 120 I have hanging around, but the scratches seemed to get worse? I am not sure if I was getting paranoid or what, but the 180 is definitely working very well and I am almost finished with the sanding.

[Trevor Davies]

Hi FaustoB.

"How do I get rid of the glue spot on the side of the fretboard? (assuming that it is a glue spot...) just sanding?"

Yes, I would give sanding a go. (240 g or 400g !)

"How do I made the grain to appear more even?" "Should I have re applied some filler again after that second sanding? and then sand again (#3) and then go with TO? or keep applying TM and sand until the desired grain fill is reached?"

I think I would give the timbermate another go (or two). When sanding I would use a sanding block (a bit hard to do in the pup cavity) - maybe the sanding in the cavity has pulled the timbermate out of the grain. If you are not staining maybe sand the timbermate off with 400 g .

On my TLA-1 I only gave it one coat - but probably should have tried two.

"I tried sanding with some 120 I have hanging around, but the scratches seemed to get worse? I am not sure if I was getting paranoid or what, but the 180 is definitely working very well and I am almost finished with the sanding."

I would sand the sides with 220 g (or higher - 400 g!). You definitely should be finishing higher than 120. I find I can use a higher grit on the sides to get rid of scratch marks.

Hopefully others will agree.

[FaustoB]

Thank you so much Trevor for your help.
All very good points and suggestions, very helpful!

[McCreed]

Sounds like you've got it sorted already, but I'll put a couple things out there anyway...

With the grain filler, I think it would be difficult to get an accurate feel for the application process in a small recessed area like a pickup cavity. Typically we're working on larger, flatter, more accessible areas like the front and back of a body. I will also add that the process generally (IME) takes a bare minimum of 2 applications, if not 3 to 4 to achieve a good level surface. I should say that this is my experience with Timbermate. There are heaps of other products now that I haven't used.

Now I know you're not going for that glass-like finish, but I think my point is still relevant in that saying a single application is not going get into every dip in the grain first go, so an uneven appearance is likely.


As for the scratches on the end grain...
For large or deep scratches, I hit it first with an electric RO sander (random orbital) to get the majority of them out. Then switch to hand sanding, and progressively going through finer grits. Something I learnt only a while ago, is go one grade finer on the end grain than what was used on the flat grain. This is more relevant for natural finishes than if painting.

Another tip is only sand the end grain in one direction, not back & forth. In the case of your bass body, I would sand from the join in the middle, down in the direction of the bottom edge. Then the same for the top half - middle to outer edge (downward if you flip the body - I find sanding down easier than sanding up - but may just be me). A "strip sanding" technique works well for this. Especially inside the horns.

Probably too much - too late, but there you go!