I think you may have mould in the flocking. Some folk favour tilex or the like, I've used a solution of household bleach and water. It finest have to be a strong solution. 

When I have done it, I chose a warm day, had the van out of the sun ( dont want the pop top hot and volatilizing the chlorine, we're not doing a WWI trench re-enactment).

I covered the top bunk and the kitchen with plastic sheeting. Used a spray bottle with the bleach solution, and had at it.

After 5 or 10 minutes I blotted off as much as I could with a towel, then sprayed again with plain water. Then another blotting. Rinse and repeat as much as you feel like.

It's a pain in the donkey, and you might have some residual bleach smell. That can bring back nostalgic memories of over chlorinated swimming pools.

My memory fails me right now, but I believe there is a less toxic mould remover on the market. Whether it works as well as bleach I can't say.

Alistair

> On Jun 7, 2015, at 4:01 PM, Jeff Palmer <jpalmer@MYMTS.NET> wrote:
> 
> Can someone remind me the best way to clean the underside of the fibreglass top? It got a bit moist and water has discoloured it. 
> 
> Thanks
> Jeff
> 
> Sent from my iPhone