Having finally found some of this cleaning compound I rushed out to the vault and found some volunteers to be cleaned. There was a foaming applicator included as you can see above, not really useful for what i'm doing but the sides are marked for mixing ratios so i may use it in future if i decide to go with a weaker solution.
The simple green was applied neat without any water. My next attempt will use a 1:1 mix with water. A small plastic container with lid was used, with in this case marines dropped in and it was left with the lid on for 6 hours before i checked it.
The volunteers, Legion of the Damned Space Marines with a nasty coat of paint, worth almost nothing in this state.
The results after six hours and a gentle brush below.
Results after 12 hours and a vigorous brush, the interesting thing is that the Simple Green hasn't broken the glue joints on a chaos arm that was thrown in as well. The missile launcher body has also not been stripped where the glue has covered the undercoat. The two smaller pieces have not been dipped to show just how much paint came off.