How can I age these metal buttons?

Nickel

Nickel

Probably brass

https://www.wikihow.com/Antique-Brass

https://www.hometalk.com/diy/bedroom/furniture/how-to-age-brass-the-easy-way-13424701

https://www.youtube.com/watch?v=vysWjIEYaQk

If it’s not plastic you can try first by brushing with a solution of steel wool soaked in a jar with vinegar for 48 hours. If you like the result you can soak your button in the solution. Then seal with mod podge or urethane or wax. You can also dry brush light strokes of paint color combinations you prefer, using white, black, grey or adding green for a verdigree look. You can also use silver leaf, fun and easy to apply.

Best to you.

Hello -that seems like an easy fix. I think it would be an excellent enhancement to the details on the buttons.

First protect the blazers fabric by making a backdrop backing. I would suggest using something like an index cards, poster board or plastic trash bag.

Snip a (+) shape to make buttonholes on your “drop cloth backing” and push the button through to expose each button.

Potentially =Use acrylic paints, or rubnbuff or nail polish to add the patina.

If you use rubnbuff or acrylics I would suggest possibly sealing with something like a spray sealer ( protecting your fabric ) or clear nail polish.

Using a darkish brown -raw umber nail polish might be the easiest - dab on wipe off the high areas.

I’ve used Rub n buff on picture frames and pewter candlesticks. It’s a waxy rub on that worked well for my needs. It can lighten or darken.

Have a look at the website possible color options, reviews Q&A to to see if it’s a product you might wish to consider if you can protect the fabric and seal up the waxy patina.

http://www.amaco.com/t/mixed-media/metallic-finishes/rub-n-buff

https://www.amazon.com/AMACO-Metallic-Finish-Ebony-0-5-Fluid/dp/B00081HYE6/ref=pd_bxgy_201_3?_encoding=UTF8&pd_rd_i=B00081HYE6&pd_rd_r=D69ZW30FXPG7FV7B3TPP&pd_rd_w=qeFGu&pd_rd_wg=0y8SD&psc=1&refRID=D69ZW30FXPG7FV7B3TPP

https://www.michaels.com/rub-n-buff-wax-metallic-finish/M10183569.html

As an example—I used spray paints and rubnbuff to age patina these silver —-dollar store bells, hopefully you can achieve a look you desire. I hope this helps.

Several ways. One use really fine steel wool to buff off the shine. Be gentle and go slow. Another way would be to mask around the buttons and spray with some kind of clear coat that has a matt finish. Not sure of the color of your garment but you could also add a darker stain and wipe it off while its wet so most of the color stays in the cracks with just a little on the high spots. Let dry before removing any masking.