A Mechanic reports he was notified he used an unapproved paint stripper on the downlock brace for the main gear of their DHC-400.

Narrative

During completion of task card; I used paint stripper part #DX586 to remove paint on the downlock brace. The task card said remove paint and did not give any limitations on what material to use; so I used the only paint stripper that I knew of in the hangar. When I came in to work the next day; I found out that the paint stripper I used was wrong when supervision held off on the same inspection due to not having the correct paint stripper. This happened because the task card did not call out a specific paint stripper to use at the time. There was no reference to the company Maintenance Manual to use specific means of removing the paint. The next day; the card got changed to specifically state which paint stripper to use. Callback conversation with reporter revealed the following information: Reporter stated his carrier has since revised the job card to reference the correct paint stripper for the gear braces and have purged the hangar of all unapproved paint strippers. Reporter stated the gear braces are made of hardened aluminum alloy that is Vibro-peened to increase strength. Incorrect paint stripper on that type of metal can cause embrittlement.