APPAREL MANUFACTURING - I 3(1+2)

Lesson 7 : Pattern Grading

Principles Of Grading

1. Pattern and grade development

The dynamics of fashion necessitates the continual development of new styles, with each of these styles requiring a different pattern. While the number of style and pattern variations are seemingly endless, all of the patterns have one principle in common, which is that nearly all of the major components are derived from basic block patterns. In other words, there is a direct relationship between a garment pattern and the block pattern which was used as a basis for developing the pattern. This relationship also applies to the grading of garment patterns.

The grading network for a block pattern is also the basic network for the components which have been developed from the block pattern. As a result, the application of the network can be considered to parallel the process of developing a styled component such as a jacket (Fig. 1).

There are many techniques involved in the grading of garment patterns but all have one common principle: the Basic Grade.

Fig. 1: Pattern development and grading applications

2. The Grading system

This principle provides the necessary accuracy and versatility required for grading patterns according to the considerable variations in customers’ requirements.

Today, the clothing industry supplies markets throughout the world and as a result, a rigid grading system built around one size chart and one size interval has a very limited value.

3. Size ranges

This term refers to the differences in the major girth measurements between the smallest and largest size in the size chart. For example: the following size chart No. 1 contains a range of women’s sizes where the total girth span is 45cm and shows the typical division of a size range into two sub-groups: regular and outsizes.

Size chart No. 1

Women’s sizes
	Regular size					Outsize range
Sizes	A	B	C	D	E	F	G	H	I	J
Bust	80	85	90	95	100	105	110	115	120	125
Waist	60	65	70	75	80	85	90	95	100	105
Hips	85	90	95	100	105	110	115	120	125	130




The division is dictated by the differences in the figurations and proportions between the two body type and it would be a fallacy to assume that a woman’s regular size could be graded through to an outsize. To perform this correctly, a large amount of pattern manipulation would be involved and this is not a function of grading. In practice, a different block-pattern would be used for each sub-size range and two or three sizes would be graded up and down from the central size for the group.

4. Size intervals

A sizing system is nothing more than the artificial division of the population into sizes groups according to a pre-determined size interval i.e, the major girth differences between each size.

Apart from convenience, the size of an interval is basically influenced by the magnitude of the garment measurement tolerances. Consequently, it would be pointless to use an interval smaller than the limits of measuring error for a major girth measurement. For Ex: a size interval of 1 cm would be capable of being measured on a pattern but in practical terms, it would be very difficult to measure it with the same degree of accuracy on a finished garment.

Therefore, if we assume that the range of size variations is in order of plus or minus 2 cm, then the logical size interval would be 4 cm. in practice, intervals smaller than 4 cm would only result in the use of more sizes for the same range.

5. Size charts

There are two types of size charts in general use:

Type 1: Body measurements
This type of chart provides the body measurements for each size and the pattern maker uses these measurements as a basis for constructing a pattern with the requisite amounts of ease.

Type 2: Garment measurements
This chart details the finished measurements specification for each size and is used for pattern grading and quality control purposes.

The standard component of a size chart is shown as below:

Size chart	Garment type: Skirt			Style No. 1234
Size / Size symbol	A	B	C	D	E
Waist	62	66	70	74	78
Hips	86	90	94	98	102
Length	59	59.5	60	60.5	61




Size chart consistency

The size chart is in effect the grading specification for garment patterns and as such, must be capable of being applied in a systematic fashion to all of the sizes being graded. The practical advantage of a consistent size interval is that it enables the grader to work with standard increments for each size, which makes memorisation easier and performance more efficient. Conversely, inconsistent size intervals introduce unnecessary complications, which would lead to possible errors and low performance levels. Therefore, prior operation in the preparation for grading would involve checking the consistency of the size intervals given in the size chart from which the grader has to follow.

Using the following below size chart as an example, the highly important subject of consistency can be developed in more detail.

SIZE CHART
(All measurements in Centimetres)

Size	A	B	C	D	E	F
Bust girth	84	87	92	97	100	104
Waist girth	62	65	69	72	78	82
Hip girth	94	98	101	106	109	114




On examination of this chart, four factors are readily observable.

• There are six sizes in this size range
• There are five intervals between the sizes.
• The measurement span for each of the girth measurements is 20 cm.
• The size intervals for each girth measurement are inconsistent.

In order to grade this range of sizes in a systematic fashion, the size intervals inconsistencies would firstly have to be levelled out. The procedure for levelling is to take the girth measurement span e.g. 20 cm and divide it by the number of size intervals, in this case five. This would produce a size interval factor of 4 cm and the resultant levelled size chart would be:

Levelled size chart
(All measurements in Centimetres)

Size	A	B	C	D	E	F
Bust girth	84	88	92	96	100	104
Waist girth	62	66	70	74	78	82
Hip girth	94	98	102	106	110	114




Which now provides for consistent grade of 4 cm between all of the sizes. However, this consistency has not been achieved without some changes, and the question is how material is these changes in practical terms?

Firstly, the basic parameters of the original size chart have been left unchanged. i.e., six sizes, five intervals and the girth measurement spans of 20 cm. what has happened is that from the total of 18 given measurements, 11 have remained unchanged and seven have changed as follows:
Five: increased by 1 cm
One: Increased by 2 cm
One: Decreased by 1 cm

The ease allowances combined with making up tolerances would absorb the differences, although the differences in waist measurements (if the garment was close fitting) cause a slight problem. In this situation decide whether these differences can be safely disregarded or some compromise is necessary. This means ‘doctoring’ of graded patterns., and in these circumstances the golden rule is to grade to one consistent girth interval, preferably the bust girth, and alter the other measurements accordingly.

From a practical point of view, size interval levelling is a prerequisite of efficient grading and it would pay to remember that there are a multiplicity of size charts in circulation and the most consistent factor about them is their inconsistency.

6. Measurements

The measurements given for a size represent the average measurements of a woman having a particular bust or hip girth, and this combination is denoted by size symbol. Therefore, grading system must automatically provide efficient and accurate answers not only for the given measurements, but also for those which are not given.

7. Nomenclature

A size is a combination of measurements and each combination is designated by a symbol which is a common ‘code’ between the manufacturer and the consumer. These symbols are alphabetical and/or numeric, and for the consumer the size symbol provides instant recognition as to whether the garment size is suitable or not.