How do i clean ancient bronze coins

[coinhound1983]

Hi, I had posted a cleaned well preserved roman coin on here earlier. However now I have 20 of these but still caked with dirt, I believe all to be bronze . I'd like to know what methods are best to clean and preserve these coins as best as possible. Any ideas would be great. Thnx

 

[wheatfinder13]

Hey, nice Romans and Byzantines you got there. I soak my ancients with olive oil and clean them with an old toothbrush

 

[coinhound1983]

Ty, I will try that on a few, what kind of olive oil? How long and what do you brush them with after soaking