Mildew in Sculptamold

[mark dance]

Looking for some advice.

Last week I covered a very large area (~50 sq ft) with plaster gauze and Sculptamold in a marathon session.  The Sculptamold is still a bit moist in most areas which hasn't worried me too much because this is what my historic experience has been.  However in one area of about 3-4 sq ft small spots of mildew have shown up and appear to be growing.  This area includes but is not limited to a spot where I experimented covering the Sculptamold with Lightweight Hydrocal "snow" and spots of mildew appear to be coming through there as well.  My concern is increasing...

What should my next course of action be?
  - should I leave it trusting the mildew will stop spreading when eventually everything dries out?
  - should I paint over it with a latex paint?
  - should I rip the section out because it has been compromised?
  - other?

thx in advance for the words of experience here...

I am also interested in any comments as to why the mildew has appeared in this one section and not historically or in other areas...

md

[Sokramiketes]

I can't imagine that a spritz of dilute bleach solution would hurt anything at this point, but it would kill the mildew.  I wouldn't paint until the stuff has dried out.

Is this a basement?  Do you have a dehumidifier running?  That's a long time for sculptamold to dry...  Mildew will probably grow on anything that is wet for a week, so I wouldn't think it's a bad batch or material problem.  Just a humidity problem.   

[mark dance]

thx for the advice...

The railway is in an insulated and heated, detached garage building.  It has a high throughput extraction fan in the roof and this was running while I was laying down the plaster and for a couple of days afterwards.  I turned it off at the beginning of the week, about the same time as I experimented with re-wetting an area for the hydrocal snow.  Interestingly the area of mildew is nearly solely limited to the overspray area which got incidentally re-wetted when I laid down the snow.  Maybe this was it.  I neglected to leave the fan on after this relatively minor re-wetting but it is on now and I have cranked up the heat to help. 

I did a bit more research and found a recommendation (creditted to Paul Doklos I believe) to mix a bit of Lysol disinfectant into plaster when you mix it to help assure mildew doesn't take root so the disinfectants are at hand as I type this.  Your idea of hitting it with some bleach is also a good idea and I will do that to try and beat it back...

Many thx again.

md

[pnolan48]

In my experience, hitting it with a bit of bleach won't hurt anything. I am concerned about the long drying times. I've never used Sculptamold, so I don't know whether it sets by evaporation or by chemical process; I know hydrocal sets by chemical process. I use good old joint compound, which dries by evaporation.

[Ian MacMillan]

When I mix Sculptamold I always add a capful of Lysol.

[inkaneer]

When I mix Sculptamold I always add a capful of Lysol.

Yeah, I add bleach to the water.  Not too much, just enough to make a dilute solution, or else the chlorine fumes will kill you.

[Rich Reinhart]

When I mix Sculptamold I always add a capful of Lysol.

Ditto...

[mark dance]

...just closing this thread out.  If any of you out there ever experience mold or mildew forming after the fact in unpainted Sculptamold, spray the area with diluted bleach.  The mildew almost literally disappeared in front of my eyes and looked to be gone within a day.  Quite a relief.

Thank you to everyone for suggestions and comments from their experience.  A bottle of Lysol is now in my Sculptamold kit.

md