How do I clean/brighten/ exterior sandstone foundation?

[KellyVega]

This is my house 1920 colonial. The foundation was covered in old tar and paint splatter. After gallons of multiple different citrus removers, some of the old toxic stuff I had sitting around and 5 rounds of pressure washing I got it off. I left a couple pressure washer gouges which show because they cut through the surface rust color. Is there anything I can use to clean/brighten the sandstone to get a more uniform color. It seems like the rust color is just on the surface. Can it be removed? I have tried baking soda, vinegar, oxyclean, clr, and, yes, a small area of acid; no dice. Any advice? Thanks

[bxbhulk]

Thanks for the replies. Its not that I don't like the patina, there is too much inconsistancy in the color and areas that are slightly gouged from grinding cement and the pressure washer.

[SamsOvar]

I had a similar issue and used a low-pressure wash with just water first, then a mix of water and a tiny bit of dish soap for stubborn spots. After that, I rinsed really well and let it dry out naturally. Learned this trick during an end of tenancy cleaning when I had to get sandstone steps looking presentable again without damaging them.