What is the effect of applying 250 °C on acidic zinc plating

Hi,
I'm a engineer at a company that sells chemicals for electroplating. And I'm a technical service and sales engineer for this company. My customer has acidic zinc plating baths. and he says that when they heat the plated parts to 250 °C, zinc exfoliates. I said him that it is normal. I know that zinc can't resist heat above 200 C. Am I wrong? If this is wrong, what is the limit temperature for zinc plated layer? Thank you for your information
Sincerely

Zinc plated deposits may exfoliate; but it is largely dependent on the substrate. Fasteners generally will not but some very bright sheet metal may. Try to keep the de-embrittlement up to a maximum of 180-200 °C.