Citric acid

[les]

Just looked at my citric acid pack, it’s out of date ! I need more. For block cleaning what grade is better, food grade or what they say general cleaning ? I was inclined to think it’s the former any thoughts please.

[svenedin]

The crystals last almost indefinitely if kept dry so I wouldn't worry about the date just for cleaning engine blocks. Food grade is purer but cleaning grade is fine for descaling a block. The made up citric acid solution does go off (microbes break it down). I used to use citric acid as a stop bath in photographic work and the made up solution had a short life.

Stephen

[les]

Thanks for that Stephen, I was surprised when I saw the apparent best before date on the pack, it was 2022 ! My main concern was leaving it in the block for a couple of weeks to find it had lost its strength, requiring starting again.

[svenedin]

Thanks for that Stephen, I was surprised when I saw the apparent best before date on the pack, it was 2022 ! My main concern was leaving it in the block for a couple of weeks to find it had lost its strength, requiring starting again.

It should be absolutely fine but one thing to consider is that as the temperature starts to fall it works rather slowly.

Stephen

[les]

Better get cracking then, the weather is changing.