yellowish stain

[Agriman]

We have a yellowish stain shows up on our swim platform in a blotchy pattern after it gets wet. It does this even after a morning dew, or a washing. We scrub with a Clorox cleaner but its stubborn until the sun seems to bleach it out in about 2 hrs.. Had a fiberglass man look at it and he has never seen this before. Anyone ever have this problem? The fiberglass guy suggested he could apply a thin gel coat over it but no guarantee that it would not come back.

[Midnight Sun]

This may an indication of a previous gelcoat repair job. They never change color with age the same as the original. if it bothers you this much get it recoated as you suggested.

[tomschauer]

I am not sure if the 1998 mariner has a solid glass platform or laminated plywood. If laminated, the blotching would indicate moisture between the glass and wood (delamination). Find out where the moisture is getting in (most likely at the fasteners that support the platform or a crack in the glass) dry completely and rebed all fasteners. If it has a solid glass platform, disregard the above.

[waybomb]

Try cleaning it with a very mild acid - could be iron deposits rusting. The acid will dissolve the iron.

[Agriman]

Thanks for the suggestions. I'm leaning towards a previous repair. If it was moisture I wouldn't think the stain would show up with a bit of dew. I'll see if I can get a moisture meter and take a reading. Like I said 2 hrs of sunshine and its back to white again. If a re-coat works I'll do it at fall haul out.

[AaHubb]

" yellowish stain shows up on our swim platform " Might I suggest another half step aft on those wee hour of the morning trips to the swim platform.

[Viper]

Qr Bbpost Try cleaning it with a very mild acid - could be iron deposits rusting. The acid will dissolve the iron.

+1

If this doesn't get it out, it's a poor repair or something just under the gel coat layer. If it's something under the gel causing the issue, there is no guaranty that re-gelling will solve the problem long term.