Auto body repair & detailing: Tinning for lead work, lead work, baking soda

Question
How important is it to wipe the tinning off after it turns brown from the heat before you apply the lead? Will the lead stick good if you don't? I cleaned the tinned area really well with baking soda paste before I applied the lead.

Answer
Marge, I'm a little confused by  your question. You tin the steel with acid core solder, well beyond the area you intend to lead. Then, apply lead directly over the solder. I think the brown stuff you are seeing is the actual acid flux, and nothing in my training ever indicated that this should be removed. You can try cleaning it off first before leading, I don't think it will hurt, but it's an unnecessasary step. I think you might actually potentially cause the new lead to not want to adhere to the solder. I always wet sanded the lead to remove and neutralize the flux after the lead work was finished, sanded, and ready for primer. Bill