Platinum refiner Johnson Matthey has had a strong start to the financial year, but the company, which sells catalysts for cars, warned that second quarter results may be affected by reduced consumer confidence.Sales in both the environmental technologies and emission controls divisions the in the three months to June 30 were up by 39% from the same period the previous year, with catalyst sales performing strongly.The precious metal products division saw sales rise by 34% benefiting from robust platinum group metal prices and good demand for industrial products and precious metal refining. Average platinum prices were up by 34% on the same period the previous year.'Looking ahead, for the group as a whole the second quarter will also be significantly stronger than the same period last year,' the company said. 'However, we currently expect that its results will be lower than those in the first quarter due to normal seasonal factors, an expected end to recent stock building by the car companies and the potential impact on consumer confidence of economic uncertainty, particularly in Europe.'It said that the outlook for the second half of the year is harder to predict but if demand remains at current levels full year results will be well ahead of last year.