Touch up?

[bugbear]

I don't want to strip and refinish this because of the (pre 1970, who knew Yamaha was so old) brand name.

So - is there anyway to improve this?

EDIT; this is the guitar where I needed to remove and repair the broken screws.

what-metal-is-a-telescopic-aerial-made-of-t96804.html

BugBear

 

[profchris]

I'd begin by wiping on some naptha or white spirit to see how that looks. If ok, a few coats of clear shellac, just wiped on, would be my choice.

The original finish is likely to be nitrocellulose lacquer, and if so then in theory a thin coat of the same might burn in almost invisibly (this is reading, I don't use nitro). It could be polyester, first used mid 60s, in which case CA is said to work to fill dings and scratches. Again, theory only.

If it is near abrasive-proof it's polyester!

 

[thetyreman]

you could very lightly sand it and just remove the varnish layer, the problem though is making it match with the rest of the neck and guitar, and overlap where the front meets the sides, with shellac it takes a lot of skill to get a seamless transition, that's been my experience of it so far, but I'm quite new to using shellac so not the best person to ask, it does look beautiful though after 3-4 layers.

 

[bugbear]

I'd begin by wiping on some naptha or white spirit to see how that looks. If ok, a few coats of clear shellac, just wiped on, would be my choice.

The original finish is likely to be nitrocellulose lacquer, and if so then in theory a thin coat of the same might burn in almost invisibly (this is reading, I don't use nitro). It could be polyester, first used mid 60s, in which case CA is said to work to fill dings and scratches. Again, theory only.

If it is near abrasive-proof it's polyester!

OK - so a key question prior to any action is identification of the current finish.

Info so far;

• alcohol will dissolve shellac
• alcohol won't dissolve nitro-lacquer
• Lacquer solvent (including naphtha, xylene, toluene, acetone, various ketones) will re-dissolve lacquer

Edit; found this:

Wood that has an oil finish will absorb linseed oil. If a small amount of linseed oil applied in an inconspicuous area beads, rather than absorbs, then it is probably not an oil finish and is likely shellac, lacquer, varnish or polyurethane.

Use a clean cotton swab dampened with acetone, and apply in an inconspicuous spot. If the acetone beads, it is most likely a polyurethane coated wood. If it doesn't, observe the spot over the course of a minute or two. Shellacs and varnishes will become tacky, while lacquer will dissolve completely. Finally, to differentiate between shellac and varnish, use a clean cotton swab to apply denatured alcohol. Varnish will react slowly, but shellac will dissolve right away.

BugBear

 

[MIGNAL]

Chances are it's NC. NC has a strong tendency to crack over time. Someone needed to give me a £1 for every time I've come across a guitar with a cracked NC finish.

 

[bugbear]

Chances are it's NC. NC has a strong tendency to crack over time. Someone needed to give me a £1 for every time I've come across a guitar with a cracked NC finish.

Can I apply more NC like I could apply a new layer of French Polish, and consolidate the existing coat(s) ?

If so, do I need to brush or wipe?

I've never used the stuff :-(

BugBear

 

[MIGNAL]

Try the acetone, hopefully it will meld the finish cracks. Just try it on one very small area.

 

[ED65]

If so, do I need to brush or wipe?

Nitrocellulose is a spray-only finish.

Further to the suggestion above about using acetone to hopefully meld the finish, one trick to 'mellow' the effect of a solvent (edit: remembered the right word, it's buffer) is to blend it with something else. Many commercial slower-drying lacquer thinners rely on this.

You can mix it with meths or white spirit for this purpose. You could use water too and although acetone will mix readily with water but I think it's best not to here for a couple of reasons.

 

[bugbear]

Ever happy with an excuse to take photographs using attachments and gadgets, here's a close up of the top-of-the-A

BugBear

 

[MIGNAL]

That looks more like a chip, the finish actually delaminating. You can drop fill that but you really need to find out what sort of finish has been applied in the first place.
What effect did the acetone have?

 

[bugbear]

That looks more like a chip, the finish actually delaminating. You can drop fill that but you really need to find out what sort of finish has been applied in the first place.
What effect did the acetone have?

The top of the 'A' (as you can see from the first "overall" shot) is the only chip; I was hoping it would show the thickness of the film, and the nature of the chip texture. The closeup also shows areas of cracking/peeling of the finish.

Do I need "proper" acetone, or will SO's nail remover serve?

BugBear

 

[MIGNAL]

I buy Care+ Acetone. Some of the nail polish remover might be mixed with other stuff. I once bought some polish remover to dissolve superglue and it was no way as effective as the Care+, which I assume is just acetone.

 

[bugbear]

I buy Care+ Acetone. Some of the nail polish remover might be mixed with other stuff. I once bought some polish remover to dissolve superglue and it was no way as effective as the Care+, which I assume is just acetone.

Thanks for the info; I just trawled town in my lunch break. Nail varnish remover normally has (at least one of) water, glycerine, lanolin added, amongst other things.

A pharmacy provided me with 50 ml of acetone - Care Plus brand!

It appears that good sources of supply for larger amounts would be nail car suppliers (it's not used to remove varnish,
but to work with artificial nails and glues) and fibre glass resin suppliers.

BugBear

 

[MIGNAL]

Try the acetone, see how it works with those cracks. The peeling might be more difficult.
You'll probably have to drop fill the chip, either with NC or maybe even superglue. Superglue will probably leave a visible edge. Depends how exacting you want to be. It's only a Yamaha. Commercially this would not be a viable repair.

 

[bugbear]

Try the acetone, see how it works with those cracks. The peeling might be more difficult.
You'll probably have to drop fill the chip, either with NC or maybe even superglue. Superglue will probably leave a visible edge. Depends how exacting you want to be. It's only a Yamaha. Commercially this would not be a viable repair.

Not a problem.

I think I spent over 8 hours on the tuner screws, spread over 2-3 weeks. Commercial suicide for a luthier, but a fascinating pastime for me!

BugBear

 

[marcros]

I buy Care+ Acetone. Some of the nail polish remover might be mixed with other stuff. I once bought some polish remover to dissolve superglue and it was no way as effective as the Care+, which I assume is just acetone.

Thanks for the info; I just trawled town in my lunch break. Nail varnish remover normally has (at least one of) water, glycerine, lanolin added, amongst other things.

A pharmacy provided me with 50 ml of acetone - Care Plus brand!

It appears that good sources of supply for larger amounts would be nail car suppliers (it's not used to remove varnish,
but to work with artificial nails and glues) and fibre glass resin suppliers.

BugBear

i got mine from a fibreglass supplier. 2 1/2 litres IIRC for a few quid.

 

[ED65]

A pharmacy provided me with 50 ml of acetone - Care Plus brand!

For future refs if you need more, Poundland may stock pure acetone in 250ml bottles. Our equivalent of it over here does (this is a chain owned by Poundland so the stock may be nigh-on identical).

As you've discovered one of the problems with polish remover is that to begin with it's primarily a blend of water and acetone, which alone comes with the usual risks of introducing water to the wood. The additional moisturising ingredients might pose adhesion problems in addition to that.

 

[bugbear]

Yay, Acetone!

Not perfect, but very much improved.

BugBear

 

[Graham Orm]

I don't want to strip and refinish this because of the (pre 1970, who knew Yamaha was so old) brand name.

So - is there anyway to improve this?

EDIT; this is the guitar where I needed to remove and repair the broken screws.

what-metal-is-a-telescopic-aerial-made-of-t96804.html

BugBear

Yamaha have been making instruments since the late 1800's and motorcycles since the 1950's.