8400 Demonstrate Knowledge of Vegetable Tannage

Explanatory notes

Version 3 of this unit standard introduced criteria for merit. Wherever a merit requirement appears in this unit standard it assumes that the requirements for credit have been met.

Outcomes and evidence requirements

Outcome 1

Demonstrate knowledge of vegetable tanning agents.

Evidence requirements

1.1 Vegetable tanning agents are discussed in terms of their origins and leather making properties.

Credit mimosa plus two others, which may include but is not limited to – quebracho, chestnut, myrabolams, valonia, sumach.

Merit plus bisulphiting.

1.2 The key differences between condensed and hydrolysable tannins are described in terms of their tanning properties.

1.3 The suitability of different vegetable tanning agents for specific leather types is explained.

Credit two of the following – sole leather, insole material, upholstery, saddlery, case leather, belt, industrial leather.

Merit plus one other.

Outcome 2

Demonstrate knowledge of mechanism of vegetable tannage.

Evidence requirements

2.1 Mechanism of vegetable tannage is described in terms of penetration and subsequent fixation to skin.

Outcome 3

Demonstrate knowledge of vegetable tanning practice.

Evidence requirements

3.1 Process method for vegetable tannage is discussed in terms of procedure and key principles.

Credit one of the following – counter current pit system, combined pit/drum method, rapid drum method.

Merit plus one other.

3.2 Tannage control parameters are described in terms of vegetable tanning practice.

Credit three of the following – acidity, salt balance, tans to non-tans ratio, tan strength, temperature, time, mechanical action.

Merit plus two others.

Outcome 4

Demonstrate knowledge of vegetable tanned leather characteristics.

Evidence requirements

4.1 Vegetable tanned leather is described in terms of chemical and physical characteristics.

Credit four of the following – anionic, thermal stability, shape retention, substance, dyeability, water resistance, strength, stretch, lightfastness, abrasion resistance.

Merit plus two others.

This unit standard is expiring. Assessment against the standard must take place by the last date for assessment set out below.

Status information and last date for assessment for superseded versions

This CMR can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.

Please note

Providers must be granted consent to assess against standards (accredited) by NZQA, before they can report credits from assessment against unit standards or deliver courses of study leading to that assessment.

Industry Training Organisations must be granted consent to assess against standards by NZQA before they can register credits from assessment against unit standards.

Providers and Industry Training Organisations, which have been granted consent and which are assessing against unit standards must engage with the moderation system that applies to those standards.

Requirements for consent to assess and an outline of the moderation system that applies to this standard are outlined in the Consent and Moderation Requirements (CMR). The CMR also includes useful information about special requirements for organisations wishing to develop education and training programmes, such as minimum qualifications for tutors and assessors, and special resource requirements.