Hi,I recently queried sikkens primer plus primer/uc about it being used over existing coatings and dcdec kindly replied I all also emailed sikkens and they said it should only be used over bare wood I'm a bit concerned now as I have done a few jobs and used it over existing coatings,I always thought this was right as is states it's an undercoat has anyone else done this or have I messed up,many thanks