How can I brighten up a cheap white cardigan?

[FuckingHateRats]

Last year I bought an oversized fluffy white cardigan from H&M. It wasn't expensive but it's lovely and I haven't yet found a better quality replacement.

It's looking a little dull/tired.

Is there anything I can do - tried and tested - which will work to brighten it up? It's an acrylic blend.

Thank you!

I saw something on Facebook a few years ago which I have used a few times. Has really brightened some clothes, not worked so well on others, but hasn't ruined anything. Unfortunately precise volumes weren't given in a 'just chuck it in' kind of way.
To a bucket of hot water, add white vinegar, bicarbonate of soda and washing powder. Mix, soak garment for a couple of hours, rinse.

Sew on some quirky buttons? Dye it?

I use vanish crystal white on my whites... seems to brighten them a bit

How many buttons does it have? Brightly coloured odd buttons can work wonders. The more colours the better.

It has lovely chunky dark buttons that I like - it's more that the fabric itself has lost its brightness. Thanks for the product and soaking suggestions - I'll try both!