Refinishing sire bass and filling cavities

[brickers]

I have a sire jazz bass that I routed some wood out of for new pickups. I’m considering routing out yet more wood for different pickups. Sooner or later I want to repaint the body and fill the unused cavities and I’m just wondering the best way of doing that. The plan so far is to fill the cavities by gluing in wood blocks, lightly sand most of the body, and completely sand the front, then use car paint spray cans for the refinish. My concern is that over time there might be some join visible on the front if there is wood movement - I’m going for a pickguardless look. Is it worth finding some very thin sheet wood to glue over the front? For example Hobbycraft have sheets that are 1/32 of an inch thick. 
 

Does anyone have any experience of refinishing sire bodies? Are they known to be polyurethane? And if so am I right in thinking they can be painted over as long as they’ve been sanded to give the paint something to hold onto? Would this apply to the headstock too - I’d like to match the body colour and I’ve GOT to get rid of that terrible shape…

[BlueMoon]

1 hour ago, brickers said:

and I’ve GOT to get rid of that terrible shape…

This would be the most important thing on my list........being the totally shallow creature that I am.

[brickers]

4 minutes ago, BlueMoon said:

This would be the most important thing on my list........being the totally shallow creature that I am.

Absolutely. Takes a swathe of inexpensive basses off my shopping list, sadly. But I cannot get over it since some Canadian on talkbass compared it to a moose head

[MichaelDean]

Just now, brickers said:

But I cannot get over it since some Canadian on talkbass compared it to a moose head

That kinda makes me like it more 😅

 

They're definitley going to be poly, so yes, you should be able to scuff it up and paint over the top of it.

[brickers]

25 minutes ago, MichaelDean said:

That kinda makes me like it more 😅

 

They're definitley going to be poly, so yes, you should be able to scuff it up and paint over the top of it.

Thanks Michael. 

[tauzero]

On 18/06/2025 at 08:07, brickers said:

Would this apply to the headstock too - I’d like to match the body colour and I’ve GOT to get rid of that terrible shape…

 

Sire have actually come up with the solution to that themselves.

 

[JPJ]

Shrinkage is almost inevitable. One of the best luthiers/refinishers in the business filled an aftermarket battery compartment on a bass before refinishing and even he suffered from shrinkage or print through showing the outline of the filled area. There are ways to avoid this using a skim of epoxy filler, but this will add weight, definitely affect resonance, and may itself crack down the line. A safer method might be to veneer the front of the bass after filling the cavities, this would probably be my preferred method but then you have to deal with the edge of the veneer, itself another challenge. 

[brickers]

Thanks @JPJ  

 

my current plan, created with the help of ChatGPT and to be validated by the lovely people of this forum is to fill the cavities with wood blocks and wood glue, then epoxy glue a veneer over the entire front. (Using epoxy because it’ll glue both wood and polyurethane) I was wondering how to deal with the edges without either dulling my nice chisels, or sanding ineffectively at it and potentially sanding the existing body because it’s possibly softer than the epoxied veneer edge. I also hadn’t considered cracking though I’d hope that as this would be a thin glue layer that might be mitigated. This is pure speculation though