2nd Build SHB-4

[blinddrew]

I've been giving it a very light rub to tackle any dust, but I don't think it's a delamination problem, it was coming off completely - a dozen layers back to the wood.

[Simon Barden]

I had that with some water-based poly varnish on the small bass cab I made. Started to sand and huge sheets came off, apart from in some areas where it was resolutely stuck really firmly and took ages and a lot of effort to sand off. I have no idea why that happened, except that there are times that the universe really hates you.

[blinddrew]

Given the way other things have gone today I think your last point may be on the nail.
I do wonder if the pretty wild temperature swings we're having might not be helping though? Friday it was about 30 here, Saturday peaked at 15.

[Stuart D]

Hi Drew

(From my limited experience of guitar building, but reasonable experience of wood finishing)

Was your grain filler oil based? You shouldn't really mix oil based products like the grain filler, with water based products like your poly, over the top, as they don't adhere very well (think of rain on oil patches on the road) and that could be why it's not taking to it properly.

If that's the case, you might need to sand it back down (I mean who doesn't relish the opportunity to do more sanding, right?) and then use an oil based poly for the finish. Alternatively a sanding sealer might work after the sanding, but tbh, I'd keep all the products compatible. Just makes for less problems.

If your grain filler is water based then I'd still do the same. You can use oil based finish over water based filler - just not the other way round.

I used this. https://www.sailboats.co.uk/internat...iginal-varnish

Not expensive, smells nice, thins perfectly with white spirit and lasts for years if you do another one. (You won't use the whole tin)

[blinddrew]

Stain, grain filler and poly all water-based. Given the standard of the craftsman, I'm reluctant to blame the tools...
I think I've rescued it to a state that I'm happy with. Just need to be really careful with the intermediate sanding.
If I do balls up again I shall take your recommendation on board.

[Stuart D]

That's fair enough. Hope it works. I must confess I'm not a fan of water based stuff. I found the grain filler goes off so quickly, it's hard to use. And the only advantage of water based varnish over thinned oil based varnish is the lack of odour, which isn't generally an issue for guitars.

I like the colour. Looking forward to seeing the finished product.

[FrankenWashie]

....and lasts for years if you do another one. (You won't use the whole tin)

Surely, the fact of not using the whole tin is a tacit inducement to insure that another one does indeed get built?

[Stuart D]

Surely, the fact of not using the whole tin is a tacit inducement to insure that another one does indeed get built?

Yes but I didn't want to go too strongly into that at this stage, bearing in mind the issues he's having with this build!!

[blinddrew]

Considerations for the state of my mental health are well founded!

[Ricky]

I second Stuarts call re International varnish. I have used it for 50 years on my past boats and never had a problem. I normally use the 2-part varnish - it just lasts longer and cures quicker but is 4 times the price.

Cheers
Ricky