How would you yellow (age) a poly finish?

[ruger9]

It's a Fender Vintera, I assume it's polyurethane. On some (vintage guitar) colors, I like how they yellow and slightly change the base color... by yellowing. Is there a way to simulate this with a polyurethane finish? I've got a shell pink thinline I'd like to do it on.

 

[dogmeat]

sit in a small room with it and chain smoke Camel straights for a couple months


sorry... I got nothin'

 

[Hodgo88]

Iver never done it, but if vintage guitars yellow because the clearcoat ambers with age, then why not shoot a very soft amber lacquer over the top? You can shoot right over poly after scuff sanding.

 

[jfgesquire]

sit in a small room with it and chain smoke Camel straights for a couple months


sorry... I got nothin'

That's about right. My Rickenbacker is poly and the finish over the binding turned a nice tobacco amber playing in smokey bars in the late 80s early 90s.

 

[Hodgo88]

The only problem I see is that red paints tend to lose a little saturation in addition to yellowing of the clear, so it won’t look like a vintage guitar that got a lot of UV. It might go more coral.

 

[philosofriend]

I can't think of a way to speed up the yellowing. It is caused by ultraviolet light, but what are you going to do? Take it to a suntan parlor and ask for a long strong dose? Put it outside in the sun for hundreds of days? Both ideas seem risky to me.

If you spray amber finish on it, put it on in layers mixed with not much lacquer and not much yellow either. After every weak layer ask yourself if it is yellow enough. Too much amber would look strange. So build it up in many thin weak layers.

Do you want to experiment on what is probably a really nice instrument? If it is not that valuable and you hate the look now, go ahead. You could really kill the resale value though.

 

[Blue Bill]

Throw it in the smoker for a couple hours? Wait stop, this may be a really bad idea. It could totally ruin the guitar, or even burn it to a crisp. OTOH, it might yellow it a bit. I would use tone-wood chips. At least it would smell like ribs.

 

[Milspec]

sit in a small room with it and chain smoke Camel straights for a couple months


sorry... I got nothin'

Joking aside, that is probably the most effective way to accomplish it. An added benefit would be that you would never have to worry about mold as it cannot live on nicotine stained materials.

 

[ndcaster]

shellac sticks to everything

 

[ruger9]

Iver never done it, but if vintage guitars yellow because the clearcoat ambers with age, then why not shoot a very soft amber lacquer over the top? You can shoot right over poly after scuff sanding.

Yeah, that's the conclusion I came to, I'd rather not FINISH it if I could avoid it... I was thinking how people use shoe polish to "vintage tint" maple necks...

The only problem I see is that red paints tend to lose a little saturation in addition to yellowing of the clear, so it won’t look like a vintage guitar that got a lot of UV. It might go more coral.

Coral wouldn't be bad. It's not my goal, I'm just thinking of relicing the whole thing, so I was wondering how I could do that with a poly finish.

shellac sticks to everything

That's true... I've used alot of shellac (not on guitars)... I'd have to research shellac over polyurethane.

 

[Peegoo]

What does it is UV exposure and natural degradation of the finish.

Anything you do to artificially degrade the finish will look artificial. The only practical way to do it would be to shoot a tinted clear overspray over the existing finish. But this also looks artificial because if you examine any real-deal yellowed finish on a guitar, the yellowing is not consistent; it's often blotchy and uneven. But we don't really notice that unless the finish is consistently yellowed or faded--and then it looks fake.

The best way is to do a refin or overspray, followed by some very light detail work with an airbrush to create that uneven color distribution.

Spend some time looking at some clear pics of vintage guitars and you'll see what I'm describing here.

 

[ndcaster]

Yeah, that's the conclusion I came to, I'd rather not FINISH it if I could avoid it... I was thinking how people use shoe polish to "vintage tint" maple necks...



Coral wouldn't be bad. It's not my goal, I'm just thinking of relicing the whole thing, so I was wondering how I could do that with a poly finish.



That's true... I've used alot of shellac (not on guitars)... I'd have to research shellac over polyurethane.

I've done the reverse: poly (clear matte) over shellac.

 

[Hodgo88]

Yep dewaxed shellac will stick to poly (under it or over it)

 

[fretknot]

Get a lot of bar gigs and wait 12-20 years....wait, they don't allow smoking in bars anymore, do they?

Seriously, Peego has a good suggestion. Using an airbrush would be a way to make subtle changes to the finish. It will look like a touch-up or a faux distressed finish. If that's what you're after, then it's one way to fake what time will do naturally if you can't endure the wait.

 

[ndcaster]

Peegoo as usual is right about really having to work the situation. Think of it as an art project that has no quick solution.

 

[jrblue]

...why not shoot a very soft amber lacquer over the top? You can shoot right over poly after scuff sanding.

I have done exactly this, with excellent results. But beware! Some so-called "amber" nitros are really very yellow indeed, and depending on what they're shot over, and how heavily, you can drift pretty far from a mellow amber to a urine-like, bright yellow. Practice first.

 

[Emster]

Buy the guitar 15 years ago and live in the Tropics. Always works for me here...

 

[ruger9]

I have done exactly this, with excellent results. But beware! Some so-called "amber" nitros are really very yellow indeed, and depending on what they're shot over, and how heavily, you can drift pretty far from a mellow amber to a urine-like, bright yellow. Practice first.

Too bad I have nothing to practice on, other than the back of the guitar itself lol

 

[Boreas]

IIRC, Poly is typically designed to NOT yellow much with age or even allow a great deal of UV to get to the base for the wood or paint to yellow. I think it partially filters UV - but likely varies with the product used. So I think the only way to get yellowing fast is a tinted overspray.

 

[ruger9]

IIRC, Poly is typically designed to NOT yellow much with age or even allow a great deal of UV to get to the wood. I think it partially filters UV. So I think the only way to get yellowing fast is a tinted overspray.

Right. Simply letting it sit in the sun ain't going to do it. The lacquer overspray is probably the only way. Not sure I want to mess with that. I've refinished a guitar before, and it came out well, but it's a real PITA. I was really hoping something (product, technique) existed to yellow it quickly and relatively easily, like with maple necks. But apparently no such thing exists.