mildew on sikkens

I have a homeowner who has a log home sealed with sikkens cetol 1 with mildew on it. my question is can I use a bleach wash without damaging the finish or do i need to strip it. He wants to seal again after the wash. he sealed with cetol 1 when new, now sikkens has informed him that he needs to use cetol 23 for UV protection for the part of the country we are in. any advice would be great I need to get back with him soon.

Sikkens

Any thing you use to clean the mildew may take some of the finish off. The problem is putting a sealer over sealer. You will not get the results that are expected (finish and durability). Unless you contact sikkens and they say otherwise. I would remove the finish on the home before resealing.

milde on sikkens

Walter I am not resealing the house the home owner will be doing that. It is my understanding that sikkens told him he could use cetol 23 right over top of the old cetol 1. thats not my cup of tea so Iam not getting involved with that. thanks for the advice I will pass it on to the homeownwer.