Hypertufa How To

Hypertufa Glossary

May 8th, 2008 by Seb Brown

The following is a glossary of terms used when making Hypertufa. If you think there is something missing from the list please add a comment below.

Accelerator – Ingredient added to increase the hydration and to shorten the set and cure times.
Admix – See Admixture.
Admixture – Generic term for any non-bulk material added to Hypertufa. It is also an abbreviation for acrylic bonding admixture, which increases strength while reducing moisture absorption in Hypertufa.
Aggregate – Any dry bulk material added to Hypertufa other than Portland cement and sand.
Air Entraining Agent – An ingredient that can be added to a Hypertufa mix which captures miniature air bubbles during the mixing process. This reduces the harmful effects of freeze-thaw cycles.
Alginate – A one time use mould making material used primarily for body casting.
Armature– A “skeleton” or support structure for large Hypertufa projects.

Bug Holes – Small holes found in Hypertufa castings caused by air bubbles.

Casting – The end product of the moulding process.
Cement – See Portland cement.
Chicken Wire – A light galvanized wire fencing usually made with relatively large-sized hexagonal mesh. Can be layered around an armature to hold the Hypertufa mix in place and strengthen the structure.
Closed-Cell Foam – A hard, non-absorbent foam.
Compressive Strength – The ability of Hypertufa to to withstand a downward force or to sustain a heavy weight.
Concrete – A mix of Portland cement, sand and water. The standard construction recipe calls for one part Portland cement to three parts sand/shingle.
Concrete Admix – See Admixture.
Cure – The process by which Hypertufa hardens; dependent on sufficient hydration and temperature.

DWT – Drywall tape.

Efflorescence – Salts which leach out of Hypertufa during the curing process.

Faux Bois – Imitation wood (French).
Form – Mould used for setting the outside shape.

Grot – An Abbreviation of grotesque, They look like gargoyles but instead of being used as rain spouts they are used as planters.
Green – Uncured.

HWM – Hardware mesh, cloth. Used to reinforce larger Hypertufa projects.
Hydration – The chemical reaction between water and Portland cement.

Model – An original piece used to make a mould.
Mould – A rigid structure used to hold green Hypertufa into a fixed position until it sets. See also positive mould, negative mould, mother mould.
Mortar – A variation of concrete used in masonry; it does not contain rough aggregate.
Mother mould – Outer, often rough mould made of the back of a mould. Used to secure the mould during the casting process when it is made of flexible or fragileĀ  material.
Moulage – A reusable mould-making material that is used primarily for body casting.

Negative Mould – The casting of a model which is made to create a positive mould. Used when the original model is fragile and requires the use of non-durable moulding material.
Nylon Fibres – Added to Hypertufa add strength and cohesion.

Perlite – Volcanic glass superheated to form a lightweight aggregate which can be used in Hypertufa. Has a high moisture content.
Plasticizer – An ingredient that can be added to a Hypertufa mix to increase it’s workability.
Portland Cement – A powdery substance that is produced by burning a mixture of clay and limestone at a high temperature. It is a primary ingredient in Hypertufa.
Positive Mould – A concave mould which prevents the escape of the moulding material during the moulding process.

Rebar – Steel bars usually used in concrete to provide reinforcement. Can be used to make an armature in Hypertufa projects.

Sand Casting – The process of manipulating sand to create a mould and then filling the mould with Hypertufa.
Silicon Dioxide – Can be added to a Hypertufa mix to increase density and water resistance via a chemical reaction.
Slurry – A paste made with Portland cement and water.
Set – The initial hardening of Hypertufa before it has fully cured.

Tufa – Naturally occurring soft or porous rock formed by water deposits. Hypertufa is an artificial version of Tufa.

To get more information on different Hypertufa projects I recommend The Hypertufa How To Manual by Claudia Brownlie.

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What is Hypertufa?

February 9th, 2008 by Seb Brown

So what is Hypertufa?

Well, Hypertufa is an artificial stone used for making, amongst other things, garden ornaments, pots and troughs. It is made from various aggregates and bonded together with Portland cement. It’s used as a alternative to natural tufa, which is a slowly precipitated limestone rock.

A Hypertufa pot is very porous which makes it good for plant growth. It is also fairly light in comparison to other pots made from terra cotta or concrete and can cope with low temperatures down to -30C.

I hope that gives you a quick overview of Hypertufa. You can find further information about Hypertufa on this site. Also I highly recommend The Hypertufa How To Manual by Claudia F. Brownlie.

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