Hi,
i use a papercrete topcoat on my ferrocement sculptures and have experimented a little with waterproofing the finished sculptures- two things i have tried successfully were:
crommelin waterproofing natural finish penetrating sealer- seemed to do the job but was smelly and needed solvent cleanup which i wasn't keen on but it says it's waterproofing compounds are taken below the surface hence 'penetrating'
and
sure seal aerosol tile and grout sealer which is technically for mosaic work (voted best in industry according to the can) I wasn't too happy about the can but it didn't require a toxic solvent clean-up episode. It wouldn't be any chop for large areas due to the size of the can.
I don't yet know if they would require recoating at some time- a basement is on a considerably different scale compared to a sculpture.
Bill Birdsall did some roofs and i think tunnels using 'nylon cement' in Puerto Rico- it was fishing net and portland slurry-http://www.naturalbuildingblog.com/nylon-cement-roofs/ this link is about roofs but i am sure he did some under ground level tunnels, too- maybe a hybrid approach would work?
I keep returning to the idea of using magnesium phosphate cement in place of portland in the papercrete which i have not been able to test as i haven't been able to source the materials but in the US you can buy grancrete which as i understand is the stuff all mixed up and ready to go- as it makes a chemically bonded ceramic which is impervious to water down to 10 microns from memory, in theory it would produce a waterproof papercrete. If you google Michael Collins, an artist who lives in Mexico, he has done some interesting work with magphos cement.
The other thing i plan to try out is Silasec waterproofer by Bondall- it doesn't seem to be a penetrating sealer but has recipes on the container for waterproof paint and putty- says it will seal fishponds and tanks, resists water pressure, etc ( it does have a warning that it 'contains calcium chloride') I wanted to extend the 'waterproof putty' idea but haven't tried it out yet. Maybe as an ingredient in portland slurry over fishnet with a acrylic/papercrete render?
cheers, eo
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