Sep 8, 2016

Hypertufa Workshop

I will be at Hickory Knob State Park this week end for a Hypertufa and Sans-casting workshop.
Hypertufa Check list
Safety First
Dust mask,Eye protection ,Rubber or Nitrile gloves
Apron and old clothes, rubber boots
Portland cement
Aggregates :Vermiculite, perlite, PermaTill, sand, sea glass, pea gravel, sea shells
Organics:  Sifted peat moss or Coco peat, potting soil
Optional: Concrete dye, concrete reinforcing fibers, liquid acrylic fortifier

Molds: Styrofoam coolers, Pizza Box, plastics bowls, flower pots, heart shaped candy box.  
Remember this is not rocket scienceAggregates can be peat moss, coco peat, and perlite or vermiculite. I do not like perlite because it is white. The peat moss or cocoa peat must be sifted through ¼ inch hardware cloth to remove lumps and sticks. Hypertufa made with the classic proportions for mortar (1 part cement: 3 parts aggregate) has a composition of
·         3 parts Type I Portland cement
·         4 parts peat sifted
·         5 parts vermiculite or perlite
For pots 1 parts cement: 3 parts aggregate.   1 quart Cement, 1 ½ qt. Vermiculite 1 ½ qt. Peat 1 qt. water
For stepping stones & bird baths 1 parts cement: 2 parts aggregate 1 part water more or less
stressing the pot with a wire brush
To increase strength and longevity, polymer-fibers, liquid acrylic fortifier, and fiberglass fibers may be incorporated into the mixture. Add the fibers to a quart of water and mix thoroughly and add to the mix.  Other aggregate such as sand, pebbles, sea glass and crushed oyster shells can be add but they increase the pots weight. Powdered or liquid concrete dyes can be added to the water first to tint the hypertufa to resemble natural rock. Buff, red and brown are the best colors to use. Fibers that protrude from the pot after it is finished can be burned off with a lighter.
Day 2 -Distressing ( making pots look old or wore)  After you manage to get your pot out of the mold take a wire brush or file and go over the outside of your pot. This will expose the vermiculite and peat. If you do not do this your pot will look like concrete and not like aged stone. Use a tile cutting bit on the dremel
Carving and drilling holes. The pots are still soft enough to carve with power tools such as angle grinders, dremels and electric drills.  Handle with care it will be easy to break until cured.
Curing – Keep your pot damp covered with plastic in a cool place for about 2 weeks or longer. Occasionally re-wet your pot as it cures. Leave your pot sitting out for a month before planting. The slower concrete dries the stronger it will be.
Recommended reading: Making Concrete Garden Ornaments  and Creative Concrete Ornaments in the Garden by Sherri Warner Hunter. My Blog

Making a Butterfly stepping stone with plywood and aluminium flashing 
Tufa tools for stressing 

1 comment:

  1. Really great article! You have mentioned here the step for make stone bird baths. Thank you very much for sharing.