Long post ahead!
Hi there! First off, this actually doesn't seem so bad! The cracks seem characteristic of the leather, though they've likely had some dirt build up in them. And the color is maybe slightly worn off in some places. A good cleaning would likely help, maybe with some kind of cleanser that foams that could get in some of those cracks (warning, it'll likely look worse before it looks better).
If cleaning still doesn't bring it to a level you want... a yellow like this is tough because it's a light, fairly opaque color in terms of how it sits on the leather (if that makes sense!). Any penetrative dyes won't help to restore this, they'd only change the color completely. 99% of the time I like to recommend creams [Tarrago, Saphir], but because of the opaque/surface-ness of this color (again, if that makes sense, lol) I'm not entirely sure they'd do what you're looking to do. If you did try a cream, you'd likely have to start with a white then add in yellow(s) until you got a matching shade... and even then if there was still darkening on the piping post-cleaning, that would likely not change much with cream.
As for paint - I'm usually
super hesitant with paint on Bals BUT because of the characteristics of this particular color it might make sense as an option. My personal opinion w/ paint on any bag is that unless it's matched and blended well (i.e. applied sparingly in places vs blanket coating the whole bag), it might be better to avoid. If you painted the whole bag you'd end up coating the threading, which is pretty impossible to come back from. And a painted bag is, well, a painted bag.
That said, should you be determined to intervene with paint, below is what I'd recommend. I know it's not Balenciaga, but I touched up a Dior bag of mine last year that had a similar opaque surface color (in a light pink - I'll add pics at the end), and these are basically the steps I took. Disclaimer: I'm an artist so I was pretty comfortable with these materials. Go with your gut on whether for
your comfort level the below is practical advice or complex nonsense
- Color match: I'd get a few more yellow paints with varying tones, maybe some other colors (i.e. green or orange or red if the available yellow paint tones are too warm or cool) and some white & mix mix mix til you get a tone that's as close as you can get it. Oh and make sure you're working under good lighting!
- Test: You can test either by gently trying on a somewhat hidden spot on the bag or on another surface that you can hold next to it to compare. FYI, in my experience angelus (and most acrylic) paints tend to dry a tad darker than they look when wet.
- Apply: When it comes to paint application, go light. Light gradual layers are better than one big ol' plop of paint. I used a couple smaller brushes. A little goes a long way, and the less you use the more you can blend it into the bag. You won't need a lot of paint, but there is a chance what you have will start to get dry as you're working. Be prepared to mix a bit more, or have a little water handy to loosen it up. Water can also help when used sparingly to thin out the paint for applying in those lighter layers.
- Topcoat: When all done and dry, the painted areas may be a bit more matte than other parts of the bag. A light touch with some topcoat (super small paintbrush or qtip) can help even out the finish.
Here's a before/after detail of the bag I touched up w/ paint. This is post-cleaning, and you can see there are just areas where the color was worn off. Of what's visible in these pics, I touched the handles as well as some select areas inside the cannage (note: I wasn't going for "brand new", more "not as beat"). To match the shade I used a couple pinks, as well as white, black, and brown. Slight color tone diff between pics b/c the before was taken at night, the after during day:
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