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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