I have been experimenting with rhubarb as my rust removing acid. Since rhubarb contains oxalic acid I wanted to try if it would do the same job as citric acid. My experiment is by no means scientific, but the results are good.
According to sources on there web you can make your rhubarb acid by boiling chopped rhubarb with a little water and then bottle the potion. I will probably try that too, but this time I just used about five litres of warm water and then added five or six large stalks of chopped rhubarb.
The rhubarb acid does just what the citric acid does. It might not be an alternative for too many of you, but if you happen to live in a place where rhubarb grows almost wild and commonly, this is a very cheep alternative to citric acid.
It seems you have to use a lot of rhubarb to create a string acid, but aian, in my case that's not a problem.
Some pictures here: https://www.flickr.com/photos/finnbe...7645680629802/