Help! My maple neck has weird spots on it!

So, I got a couple of custom orders (1xMMB4 and 1xMMB5 bass guitars) from PBG last year. What with one thing or another it's taken us a while to really get stuck into working on them.

The necks are full maple - neck and fingerboard. I'd looked into what stains to use and decided on Tung Oil. I got the Feast Watson Timber floor Tung Oil. I tried it on some pine wood to get some idea of what it might look like and I was happy with it.

This is where I might have stuffed up, though. I sanded the neck and then smoothed it out with steel wool 0000 grade. This seemed fine to me. I'm pretty sure I got all the steel wool particles off - but it's possible that wasn't good enough and I may have ended up with some on the fingerboard in between fret and fingerboard.

Anyway, I tried staining with the Tung oil and the neck starts looking grey with grey spots. I panicked and tried sanding off to try to get the spots off. I sanded with coarse grain sandpaper and then progressively smoother until I used 1500 we-and-dry. I thought I had got the spots off at least on the back but after about 2 weeks, the spots look like they are back.

So my questions are:

1. Has anyone else seen anything like this before?
2. Is there anything I can do about it?
3. Is it possible this is in the wood itself?

Either way, I'm not going to use steel wool again on maple (I wouldn't have thought that was a problem, though). The steel wool was from Bunnings.

I'm hesitant to do the other neck until I'm confident this isn't going to happen again.

Attached is an image. It's a bit blurry, but hopefully, you can see what I mean.

Cheers,

I have seen this in another thread a year or two ago. I don't recall what the outcome was though. I'll do some searching and see if I can find it.

I can't say if it was the steel wool or not, but FWIW, I don't use steel wool for anything woodworking related, especially in guitar building. The stuff is way more trouble than it's worth for a number of reasons, and there are numerous products available now that will get timber perfectly smooth without generating a bazillion micro-sized steel fibres.

Hopefully the collective we can help you sort it out. I post back after I've had a look around.

Thank you so much McCreed. I had used steel before and had no issues which is why I wasn't concerned about using it this time. Won't be using it again though.

Cheers.

Not sure quite what it is. I've given up on steel wool as well, though in my case it was the small fibres sticking into nitro gloss, though the marks were similar to yours. The spots are probably the steel oxidising or reacting with the tung oil, but it might possibly be something else.

If it were me, I'd have another go at sanding back the finish, If you've got a strong neodymium magnet, you could then try passing it over the neck to see if it picks up any steel fibres.

I really wouldn't use wet and dry on bare wood if I could avoid it. The carbide particles themselves are grey and small and can get in small crevices. I'd sand to P240 with normal sandpaper and I probably wouldn't go further than that. If you feel you want to smooth more at this stage (I wait and just go finer on the finish), then look for the 3M Scotchbrite pads, the very fine dark red and the ultra fine grey are the equivalent of 000 and 0000 steel wool.

After sanding, I'd rub the neck down with a clean cotton cloth using turps or white spirit, which will help to remove anything still sticking to the wood.

Thank you, Simon.

That's very helpful! I will definitely give those suggestions a go.

I did some searching in the forum last night after my previous post, but didn't find what I was looking for. (the search feature is pretty ordinary, so required relying on memory (dangerous) and manual searching (laborious).
Hopefully the member than experienced the same issue will see this post!

Quote:

---

I really wouldn't use wet and dry on bare wood if I could avoid it. The carbide particles themselves are grey and small and can get in small crevices. I'd sand to P240 with normal sandpaper and I probably wouldn't go further than that. If you feel you want to smooth more at this stage (I wait and just go finer on the finish), then look for the 3M Scotchbrite pads, the very fine dark red and the ultra fine grey are the equivalent of 000 and 0000 steel wool.

After sanding, I'd rub the neck down with a clean cotton cloth using turps or white spirit, which will help to remove anything still sticking to the wood.

---

Excellent advice on the wet & dry paper on bare timber from Simon! I missed that last night. That could also be the culprit for the staining/spots.
I also would try further sanding with "regular" P240, and wiping down with a clean rag and turps, metho or naptha (Shellite here).

Awesome, thank you so much for looking, McCreed. I appreciate it! I will definitely put your and Simon's advice to good use.

I was considering chalking this one up to experience and just getting a new neck from PBG, but I'll persevere knowing that I have that option up my sleeve.

Thanks again to you both.