have a few yo-yos that aren’t that great at grinding anything i could add to them or spray on them to fix this without ruining the color?
Take some fine sand paper, say 200-300 grit and sand the surface.
I thought you wanted a textured surface for grinds.
I thought a smoother surface would create more friction.
What yoyos are you using for the grinds?
That grit will roughen the surface. You can go coarser if you like.
just rubbing sandpaper over the surface wont make it smoother…
it will make it rougher then it will get around to smoother. JHB is saying just rough up the surface.
Oh yeah, derr.
My bad.
Wear gloves.
Of course my advice applies to plastic yoyos which I blindly assumed the OP was referring to. If they’re anodized aluminum that will remove the color so the MFD Buff is probably your ticket to nirvana. I wasn’t aware of that product. For raw aluminum the sandpaper works fine.
Gloves would be the best tbh. I tried to do the sandpaper trick a long time ago, you need to be able to sand the thing evenly, which was much harder than I thought it’d be. And anything under 400 grit is gonna make it look ugly. 500~1000 grit will make the yoyo nice and satined. If you only have access to 200~300 stuff, go find some junk metal or something and make the sandpaper a little finer.
Bead blasting would be the best but you’d be better off buying new yoyo or two… or ten.
If you like to live dangerously, try the sandpaper.
People have things done for different reasons.
If it’s dinged up you can have it freshened up and ready to go in for a new ano job.
Some peeps just don’t like the way their throw feels or looks. Maybe the price was right but color is dreadful. No reason to settle. An easy safe bead blast then off to ano for what you want it to look like.
Powder coat, paint, plating are all options. Surface feel is limited with theses options but there are choices.
Use one of those paint wax stuff you spray on a car to make the paint shiny. It will grind a lot better, and smells good too.
This is what I do as well!
Can you guys link to a picture?
There are a lot of car products out there…
I just use like a basic Turtle wax for vehicles…
I just use the yoyo that’s good at grinding. And when I use the yoyo that’s not good at grinding, I make a small pouty face and avoid grind tricks. 
One Drop pyramatte… you don’t suck at grinds, but I sure wish you were better sometimes…