black dots in gelcoat

[falko]

Hi, I have 2006 Bavaria 37. On deck I have noticed regions of tiny black dots in the gelcoat. They are only seen  from  up close. I've tried with 3M Medium (cut+polish) to no avail. Do you have any suggestions how to fix this?

Regards.

[IslandAlchemy]

This is a result of pressure washing the decks. Little holes get blown in the gelcoat, and water and dirt gets into them and go mouldy.

Get some mould & mildew spray. Spray it on and walk away. A day or two later it will be gone.

[Ailatan]

I used bleach with excellent results

[falko]

Thank you both. I'm on it.

Regards.

[marioxp]

it's the first time I've heard that pressure wash causes gelcoat damage!  Was it a particularly strong pressure wash?  I wash the deck with pressure wash a couple of times a year, always before polishing, I haven't noticed anything unusual.

[tiger79]

it's the first time I've heard that pressure wash causes gelcoat damage!  Was it a particularly strong pressure wash?  I wash the deck with pressure wash a couple of times a year, always before polishing, I haven't noticed anything unusual.

I think it's more likely to be a case of micro bubbles in the gelcoat, which are then broken by pressure washing and form voids in which dirt and mould can loiter.  I had the same problem on some areas of the superstructure on a Hallberg-Rassy I owned.

[Yngmar]

I think it's more likely to be a case of micro bubbles in the gelcoat, which are then broken by pressure washing and form voids in which dirt and mould can loiter.  I had the same problem on some areas of the superstructure on a Hallberg-Rassy I owned.

Yup, that's it, plus UV degradation of gelcoat over time contributes too. A Lagoon 38 S2 had it everywhere on deck except where it was shaded by the hardtop + tent.

You definitely want to have a care when pressure washing - a sufficiently strong pressure washer will take the gelcoat right off. Waterjet cutting is used to cut granite slabs

[nightowle]

I, too, have the same problem that has plagued our boat.  So, I'll have to try the mould removal method and see if that garners success.