CAA: Christian Anime Alliance

I never thought I'd ask CAA for laundry advice, but at this point I don't know what else to do. I have an apron at work that has these old, dingy grey stains on them. I'm pretty sure they were there when they gave it to me (It has a little tear in the front, too) but around a month ago, my manager noticed and told me to bleach it so that it's completely white. So I bought bleach and tried it. I don't think it made it better in any way, shape or form. I found some OxiClean and tried that, but it still wouldn't work. In the meantime, I have been wearing the plastic disposable aprons at work, which are a bit of a pain as they flutter around everywhere and tear really easily. Aunty thinks it might have synthetic fibres in it, which apparently don't bleach very well? I've thought of using more bleach, but I don't want to completely ruin the thing.
Anyone have any advice? Or is it an impossible endeavour?

If it is synthetic, you might have to look at fabric paints. However, I'm not sure of the type of work you do, so adding yet another layer of chemicals to the apron may not be advisable. If you do, you will probably want to experiment in small patches on the reverse side to ensure the fabric paint actually whitens, doesn't make it more stiff, etc. If the stains are resistant to both bleach and OxiClean, I'm not sure what else you could try (many years ago, I found SA8 was a good cleaner, but it may not be as useful as a brightener).

Of course, counting all the effort and expense you put into cleaning your apron, you may find buying a new one is a less resource-intensive option....