How can I relic/age a white pickguard?

I've dealt with this when replacing a damaged or missing guards and knobs on vintage instruments. The problem with the popular method (coffee and other kinds of stain) is that it's uneven and doesn't really get IN the plastic well. Where it does get in, it's strong and odd looking. People tend to think aging is just from UV but plastic aging is due to a few types of reactions/degradations which change the chemical structure, some of which happen on the inside.

You can try a chemical oxidation if you know what the guard is made of (there's a few different materials used). Some plastics will oxidize from bleach and actually turn yellow. Acetone can dull the surface of PVC (even melt it if you aren't careful) and while that may not give you color, it can give you that aged/chalky texture and possibly make the surface take dye better because of it. I haven't experimented with this yet I just know from working w/ PVC.

My go-to method for dealing with this honestly just getting the right colored guard on ebay or getting an aged-looking blank and cutting it. When I have to DIY I use a stain. Coffee and household things have never worked well for me. I prefer leather gel dyes as they are strong and easy to work with. The trick is to do the scuffing AFTER. Otherwise, what happens is that the stain deposits very strong in the scuffs and looks terrible. 1,000 grit sand paper can make fine swirls. If the scuff marks look too fresh/white you can do a very brief, watered-down stain to get a little color in them. Let it sit in warm water after and clean it up really well before installing. That reverses a lot of your hard work but stain can bleed out for a while. You won't notice it until it leaves a mark on a shirt.

Best of luck, let us know what you end up doing.

I've had some success with just leaving things outside for a while.

Well, it would obviously depend on your location and the amount of weather. In the sun, yes. We also have rain, snow, etc. here. But a week or two, seeing what happens, keeping an eye on it. Or even burying it in the garden.

I was going to do it today or tomorrow. You definitely DO.

Two questions about this: I have a copper shield on the back of the PG. You think that will damage it to soak like that? And I bought some Minwax 210B (Light Oak). Is "wood dye" a different product from stain? Sounds like I should go lighter and yellower. What you're describing is exactly the look I'm after. Thanks dude.