However, the coming season we are going to be using our old mattresses so we decided to clean them thoroughly. We also try to improve the ventilation especially in the forepeak. One step in the process was varnishing the mattress boards, which originally were left unvarnished by the yard - this to improve the ventilation under the mattress. However, in my opinion the trouble is that moisture is absorbing to the unvarnished wood. At least the unvarnished mattress boards did not work in our case. Thus, we decided to varnish the mattress boards and try to improve the ventilation in other ways.
Then we started cleaning the mattresses and the boat from the mold spots. The first step was spraying the mattresses with Starbrite's mildew remover. This product seems to be efficient, but in some spots the treatment needed to be repeated a couple of times.
The second step involved ozone blasting. We took all the mattress into the boat, closed the ventilators and the door and let the ozone generator run for almost 24 hours. Then I opened all the hatches and windows for a couple of hours to thoroughly air the boat, before going down below. The ozone blaster is quite an expensive piece of equipment and since one does not need it very often so it is rationale to rent it. We got one from the company called Waterproof Solutions Oy for a weekend.
We took all the mattresses inside the boat...
...closed all the ventilators.
...and let the ozone blaster run for almost 24 hours.
The third step involved cleaning the boat and mattresses thoroughly. For the mattresses we used spray-extraction cleaner, which is a good device for deep cleaning carpets and mattresses for example. It sprays water into the fabric while it is simultaneously vacuuming the dirty water back. This unit was also borrowed from Waterproof Solutions. The company is actually specialized in sodablasting, so we decided to book them for the next autumn for full bottom paint removal.
The device vacuums most of the moisture out of the fabric. It is however a good idea to let them dry thoroughly in the sun after the treatment.