Fabric Technology - Questions Answered
A while ago a business friend asked me if I could answer some questions about Textiles & Fabrics in Commerce. These are my responses to each question below which may contain some useful tips and ideas.
Working With Textile Mills and Garment Factories
What’s the best way to work with mills and factories?
(I tell Designers and Product Developers ’s that it’s so important to communicate and not leave information to the last minute.
Always attach fabric swatches to Technical Packs / Label Fabrics and indicate what styles they are for.
Tell garment factories which fabrics to expect and when).
Most Companies begin their New Range development process with a Range Plan listing Products and Fabrics & Colours that they need for the coming season. The decisions will often be influenced by Style Forecasters and Comparative Shopping Research
In many cases Fabrics will be ordered in Bulk before Garment Styling and Actual Fabric Usage Ratings are known.
Estimates based on Known History are likely to be used in this case.
In a simple world, one Fabric and Colour could be used for a Garment Order.
In a complex business one Fabric & Colour could be used for Multiple Styles and Orders.
Fabric Management Methods will be Designed for Purpose for the business based on experience and past practice.
The Range Plans are based on a Production Critical Path and should include dates set for each activity to be completed by including Fabric Delivery Dates ,set in time to meet an eventual Production Plan or Garment Buying / Selling Plan.
This Outline Plan or Versions of it could be shared with both The Mill & The Garment Factory.
Later I will add an example of a 'Critical Path' and a 'Beginning to End Product Activity Chain' which shows one companies process.
Do you recommend any particular system to keep track of fabrics, production etc? e.g. basic Excel Spreadsheet, Zedonk Software, any other popular systems?
I am sure that there are some sophisticated Materials Planning Systems available to purchase. To be fully effective such a system would have to be able to manage items by Product, Colour, Shade, Meters / Yards and Piece Number just for the textile management part of and usage program.
I do not know of any specific Product Data Management product even though some where being developed by Cad/Cam companies such as Gerber and Lectra.
Most Garment & Textile related Fabric and Production Control Systems available will need to be 'Tailored' to suit the way a business operates its Planning of Materials and Orders by Style, Size, Colour and Shade/Blend, again as a minimum.
A Spreadsheet System is probably the way most people begin to develop their original systems.
This control system could be either Manual or Computer based.
In a Multiple Order Scenario, fabrics will be stored and planned into using say a Single Spreadsheet for each Fabric, with a facility to allocate Fabric to Orders. This process should be able to handle Part Pieces of fabric as somewhere in the processing of most Garment Orders, more fabric than is needed will have to be issued to the Cutting Room in Roll Form, requiring the unused portion of that Roll to be returned into stock for use on a subsequent order.
Some businesses will issue fabric to the nearest meter required.
Others will issue to the nearest Whole Roll.
The method used will depend on the way each business deals with many Business Specific Factors surrounding Contract Control.
In a Big, say, Denim Business, where the Garment Parts move through manufacturing without any Control Numbering, at the Fabric Inspection Stage, Fabric will be Batched into Shade Batches for use together. This extra control process will need to be included in the Stock Management System.
Where fabric is delivered to a Sub Contracting Manufacturer then another system is usually needed to control Fabric Issue and Utilisation with agreed ratings from the Contractor and Rules on how 'extras' or 'Cabbage' as it was known, is dealt with.
Cabbage (an old Rag Trade Name) is created when a manufacturer does not use as much fabric to cut the whole order as the costed rating suggests they need.
Cabbage is often created or larger when the manufacturer states the rating they require.
It is an industry term meaning the extra garments the manufacturer makes to sell somewhere else and make some extra money.
Most Large UK Retailers will have a clause somewhere in their contract to say that any extra garments, good or faulty, created this way must be sold to back to the retailer, sometimes even at a premium price, to prevent their design/products ever entering the Market Trading world somewhere.
The actual small waste material and unusable remnants resulting from the cutting process often has a small value to someone in the materials recycling game (Cashmere, Camel-hair and Wool are relatively more valuable than say Cotton or Denim) but the disposal of that waste is normally a perk of the manufacturer and left to them to dispose of mixed with the scraps of the Top and Bottom Cutting Lay Papers.
Levis Jeans factories collect all of the valuable Brass Teeth, cut out from their Metal Zips in the process, where the Waistband and Fly Base are sewn across.
These Teeth were collected and sold for scrap to enhance their local Charity Donations (or used to be so when they had factories in the UK). Not Cabbage in this case but normal recycling.
Allowing Enough Fabric for Sampling & Production
How do you calculate fabric consumption for production if only one sample size was made and garment factory has to produce several sizes for production? Is there a specific calculation to use?
Again it depends on the Process and Type of Business. I only know of these Two Methods:
- In a Fashion Business at the Design Stage there is no Fabric Volume Data available unless there is a Historical base, such a Jeans, to work from.
Therefore, Sample Fabric is usually purchased as a Roll or Half Roll for Sampling.
- In a Denim Business only new fabrics would require Sample quantities.
If the Business has to provide Salesman's Samples or do Wearer Trials then the Fashion Sample Fabric Purchase will be greater.
The Fabric Rating Used will be based on a similar style/product from the past.
Ratings should always be calculated using a Whole Pattern (left and right sides)
Using Half of the Fabric Width, This will allow the equivalent of Two Sizes to be used to measure the Sample Rating.
It is normal to Lay Half of the Pattern in the opposite direction to improve the Fabric Utilisation, but only if the Fabric can be cut in both directions without shading occurring.
In Practise,
It is good practise to always pair two sizes which average the 34 Sample Size
( Say sizes 34/34 or 32/36 or 30/38 )
If the size range was say: 30 - 32 - 34 - 36 - 38 - 40 - 42
and the Buying Ratio was: 1 - 2 - 3 - 3 - 2 - 1 - 1 Garments in each size
The Mean Average Size in that order would be a fictitious size 35
Therefore the rating used to buy fabric would be that of the nearest size above = The Rating Calculated for a Size 36 created using a Sample Lay including the Two Sizes 34 & 38.
If Production Quantities are ordered after the Design is agreed then a reasonably accurate Fabric Consumption rating can be established using one of these methods.
First the Business will need to agree a Standard or Common Buying Ratio for an Order.
Where Computer Grading is used then the Cutting Lay Planning Software will be used to quickly work up a matrix of patterns to establish and accurate average Rating for that Buying Ratio.
Most Computer Grading systems can be set to run this process reasonably automatically.
In the World of Manual Grading a method used is to weigh the Whole Master Pattern, then, Lay out the Sample Pieces on a piece of the Same Card cut to the fabric width and Rating Length and then weigh this Lay Area Card. Divide the Total Lay Weight by the Pattern Weight.
The Result will indicate the Waste %.
This Waste % can be calculated for each Pattern Size using an old style.
Using a Manual Spreadsheet to tabulate them, these amounts can be listed for each size. Then, using Mathematics, an average % increase can be calculated to cover your whole 'Costing Order Ratio'.
Once the Average Wastage % is Set, the Rating measured for any New Style would then need to be be multiplied by this Waste Percentage to add it into the Rating.
All that then needs to be added is an allowance for other 'losses' (I.e. The Lay End Loss, Losses Due to Damages (as Allowed by the Mill or from experience) and The End of Roll Waste Piece ( something just less than the Rating Length) – All best applied from past experience.
I used this method for most of my Pre Computer working life and created an individual Waste Percentage spreadsheet for each of my Product Groups ( Jacket / Trouser / Coat / etc) and in practise it was within +/- 5% of the Final Costing Rating.
Sadly I do not have a copy of this any more as it was typed sheet and was thrown out just prior to our house move.
Later I will try and include an example of another one of my Spreadsheets.
It is a 'Ready Reckoner’s' prepared for the Fabric Buyer/Garment Seller to use.
It was built using the whole Garment Costing Process and Historical Fabric Ratings.
It was used by the Buyer when Selling Garments at various Fabric Cost per Meter.
It is a little complicated as it formula are pulling information from other charts on the spreadsheet.
Re: Denim (& any other fabric that shrinks). Once you have the fabric technical info from the mill, how do you calculate roughly how much extra fabric should be ordered for samples and production?
Is it possible to calculate fabric consumption per size and how? For example, men’s raw denim jeans, in a standard Levi’s fit across 7 sizes.
If the Denim is going to be Washed in the Manufacturing Process, the Master Pattern will have been made larger to include the Expected Warp & Weft Shrinkage and therefore the Sample Rating will have been measured using that Pattern
All that the Fabric Technical information from the Mill will tell you is the Shrinkage % based on Various Wash Processes. A Factory needs to establish, by trialling, what shrinkages their own Wash Processes will produce.
Provided that the Manufacturers Process repeats the same Washing and Pressing Method then the Patterns can be confidently made larger by the test defined %.
However, a Washed Jean which is then Hoffman Pressed will adopt a Smaller Final Size than one Pressed using a Steam Air Finisher even if the wash Process is the same.
- A Hoffman Type Press, Flat Presses the Garment retaining any shrinkage incurred during the Wash Process.
In the case of Jeans the Legs are Pressed and then the tops are pressed afterwards.
The Leg Presses have one or two flat bed where the legs are laid and smoothed out then there is a head which closes onto the legs while the press goes through a pre-programmed cycle.
The Tops are then pressed using a press with a shaped buck and head. This press is operated manually as it normally takes 4 or 5 operations to press around the top.
- A Steam / Air Finisher, either Vertical or Horizontal presses the whole garment in one go.
The Waist, with the zip and/or buttons fastened, is clamped around a former and steam is blown through the whole garment to release any creasing or wrinkling. Then Cold Air is used to cool the garment and dry it.
This process tends to stretch the garment back towards or larger than its original size particularly if the wait area clamp widens during the steam in process.
This may be mitigated slightly if the Waistbands can be cut across the fabric (with rigid denim this is normally the less stretchy direction) or in the direction which is less stretchy or with a non stretch fusible added to the waistband (but would counter the benefit of a stretch waistband).
The Rating for a Given Buying Ratio of your 7 sizes will use one of the methods above to establish how much fabric is needed.
In the Factory, some of the unusable ' Roll End Loss' Fabric given for Two Size Lays, may be saved by Cutting Longer Lays ,provided that the Cutting Tables are long enough to allow use of this method.
It is good practise when designing a Cutting Room to calculate the optimum table Length needed to efficiently lay out fabric lays for the intended products. Jeans, Trouser or Coat factories will need longer tables than say Blouse or Shirt factories.
Some very large businesses with very long tables have the capability of cutting all sizes in one Lay. Levis would do this cutting 60 garments in each size (5 Dozen) and all sizes in each lay.
A Process called Step or Waterfall Spreading is also optimised in a Multi Size Colour environment where the Garments are cut using Two Size Lays which are then butted together to form a long lay.
The Cut Order Planner will set out how many plies of fabric are spread in the area of each Twin Size Block.
Some Plies may cover the whole length of the lay, others may only be spread over two sizes. It is this random but essential spreading method which produces the Step or Waterfall effect. The Cutter will then separate each block of Two Sizes before cutting the individual garment pieces.
Maximum Materials Utilisation may be gained using these creative manufacturing methods.
For selvedge denim, how much extra fabric do you need to allow for in making the same standard fit jean?
e.g. Is it approx. double the amount or does it just depend on the amount of shrinkage?
There is no difference in the Above Processes when used for Selvedge Denim.
Provided that,
The Pattern used to set the rating includes the Shrinkage and when the Sample Rating is measured, it includes the Pieces for the Whole Garment and not only Half of the Fabric as your question implies.
All Fabric Ratings should always be calculated for the Whole Garment, even if measured using only half of the Fabric Width.
How do you calculate fabric consumption for really stretch fabrics? E.g for sports leggings.
For Open Width fabrics everything said before applies to Stretch Fabrics as it does to all fabric types.
If the Fabric used however is, say, a Tubular Knit then these fabrics are often managed and sold by weight in that industry.
In this case then a Weight per Square Meter will need to be built into the end of the costing process so that the correct weight of fabric may be purchased.
Care should be taken if Geige fabric is purchased for Over-dying later as linear shrinkage may occur during the dying process but the weight may increase slightly.
Any challenges from specific fabrics? E.g. matching checks / patterns / stripes / naps / fur / bonded fabrics / fabrics with finishes / anything else?
The Sample Rating for a 'One Way' 'Napped' or Patterned Fabric must be measured with all of the Pattern Pieces laid in one direction using the procedures described before here.
The Rating for Checks will be measured using the method that the Factory uses for cutting. Depending on the quality of the fabric weaving and finishing, the sizes of the individual Checks may vary and this will influence the methods used to Spread and Cut the Garments.
It is quite common on Low Value garments for Checks to only be matched in one or two obvious places such a centre front and centre Back
For High Value Products the Checks will need to be matched everywhere seams are joined. This process requires much ' Blocking Out' of panels so that they may be fine cut after matching one by one. It is common for the rolls of fabric to be 'Ripped Across' in Panel Lengths along the same Check Base so that they may be re-laid in bulk from the hem line so that each panel will match at that point.
Sleeves will be matched to each Armhole using a Pin to locate the correct matching point of both Body Panel and Sleeve.
Pocket Parts, Collars and Facings will be matched together and to their adjacent parts .
Anything less will introduce errors.
Separate Waste % Calculations will be needed for Each fabric type and Cutting Method to establish the Correct amount of fabric to buy.
At the Factory
What do garment factories do with fabrics before cutting?
e.g. If fabrics have been sent folded, do they let fabrics ‘breathe’ or ‘settle’ before cutting?
Most Factories will undertake some form of inspection of all delivered fabrics.
Often only 10% is checked using a measuring machine to establish that all Strung Faults are included (as an allowance should have been made for each string – usually ¼ mtr). If extra unstrung faults are found then 100% inspection should be undertaken to establish the actual status and add extra stings to highlight the locations for the Cutting Team
The Width and Piece Lengths are also measured during this process and recorded for Cut Planning purposes.
Some Companies who use sophisticated Cut Planning Systems will need to measure 100% of all rolls of fabric.
Some factories who buy Folded Fabric will open it to full width using their Measuring Machine
In Jaeger Ladies Tailoring Factories all Tailoring Fabric Pieces were passed through a Steaming and Cuttling Machine to relax them. The Fabric Spreading Machines used were designed to carry both the Flat Block of Cuttled (Zig Zag) Fabric or a Fabric Roll .
Some users of Stretch Fabrics will Re Roll each piece using a Tensionless Fabric Rolling Machine recognising that there will be tension in the fabric roll leaving the mill. If this tension is left in the fabric when the garments are cut then the fabric will relax and the sizing alter, usually becoming smaller than intended.
Some sophisticated Men's Suit Makers will use Decatising Machines to re shrink their fabrics to achieve a Standardised and Low Shrinkage of only 1.5% before cutting their fabrics. Others will also Rough Cut their Garment Panels and then put them through their Fusing Press before Re Laying and Fine Cutting each piece.
Even then, some will also check the Garment Dimensions for Size part way through their manufacturing process and either re trim or sew to leave an inlay.
Jacket Side Seams and Trouser Seat Seams are two such areas this would be done.
Back in the 1960's I used to have a WIRA Steam Cylinder (Lad Test Equipment) on my Pattern Table which I would use to establish the shrinkage % in each of the many Italian Coating Fabrics which we used.
That way I could make the Coat Patterns to accommodate the shrinkage as we did not have any of the 'shrinking' equipment described above.
At that time one of our Fabrics was bonded foam backed check tweed used to make an old fashioned now raglan coat.
Another was a Reversible Imitation Fur and Wool fabric with Bound edges.
Both were big sellers in their day.
How do they check for faults?
Most companies of any size will have a Fabric Store Room where one would expect to find some sort of Fabric Inspection equipment. Here either a random 10% or 100% of the pieces would be inspected to check that all faults were identified with Selvedge Strings.
Others would leave the checking to the persons spreading the fabric.
Here, locations would be marked on the Cutting Table, alongside the Lay where the spreader could confidently cut across the fabric and then start spreading again creating an 'Overlap' in which the fault would lie.
After Cutting, these overlapped pieces, containing the fault, would be removed to the scraps bin.
In a factory cutting Tubular Knitted fabric for Sweatshirts they inspected the cut panels after cutting and withdrew to scrap whole garments with bad knitting faults. They said that faults in the underside of the tube were missed during spreading.
In some sophisticated factories I have seen faults, that had been marked by the mills using invisible florescent pencils, identified during inspection and spreading by the use of ultra violet lighting set over the Inspection and the whole Cutting Tables.
There was the old story of the lady going to a night club where florescent lamps were. She apparently had the words ' Faulty. Do Not Cut! ' written across the back of her dress.
What are the Basic Production Planning methods?
There are usually multiple planning levels used. To be financially efficient, factories need to be filled with work.
Most factory accountants will spread the running cost over the hours employed at a level of expected efficiency achievable if the factory is full of work.
A Seasonal Capacity Plan, by Factory and Product Type, into which a Range Plan can be developed with the Customer/s by the Design and Sales Team.
Once Orders start to come in the will be Allocated to Production Lines building a Seasonal Production Plan. This is where the Critical Path for procurement of all materialls is set and an Critical Path for the Product Development is set.
Monthly Forward Plan by Production Line used to Chase everything and every body.
Weekly Production Plan by Production Line to drive the factory preparation of Line Planning / Work Study / Materials Issuing / Machinery Preparation etc.
The Cutting Plan used to prepare the Lays to be Cut and the Preparation of Work Bundles, Payment Tickets etc etc.
A Despatching Plan is also needed to create the space for storage and processing in the Warehouse.
Transport Planning and Booking is another part of the Planning Process.
I’ve worked in companies who make several samples to get to final salesman samples, then handing over to production who get PP samples, which may come from the actual production line.
What are the different ‘seals’ that larger companies like M&S use e.g. Gold Seal = Final Sealed Sample?
Most companies supplying larger Retailers will go through a Sample Sealing Process of some sort. Bigger companies like M&S will demand use of their own printed seal tags. Others will use those available from the likes of Morpan and set their own colour sequence.
The Usual Sequences are:
Prototype (could be fabric Trial)
Design Sample (Used at Range Presentation)
First / M&S White Seal (First Example of Garment for Fit in Fabric Approval)
Second / M&S Green Seal (Correct for Fit Fabric and Components used to Set Contract)
Rack Samples. (Held in the M&S Buying Office Range Racks)
Other Seals used:
Pilot Order / Graded Set. (Factory trial)
Wearer Trials (QC Process)
First Production Approval (sent to warehouse for QC there to follow).
Viyella used to use: Development – White Seal – Gold Seal – Black Seal.
How do you prevent interlining from coming away from the fabrics if using fused interlining? e.g. in Hong Kong suit factories, they have humidity challenges in the factory itself and then later in the retail stores…
The Interlining Suppliers should be consulted to supply only products whose Fusing Conditions / Resins / Finishes are suitable for use in the Country of Manufacturing.
The Supplier will usually provide the Testing Conditions which the Factory/QC. must use to test that the Fusing Presses are producing the correct conditions.
This may involve the use of a Pyrometer (for testing temperature inside the press, and/or Fusing Test Strips which change colour up to the temperature being experienced as the fabric pieces pass through the press.
Each Press should be tested at least three times during the day and records of the results recorded along with details of the order/fabrics being processed at the time.
The first test should be in the Morning before production starts. That is often when the press is not hot enough.
Again it should be tested after any prolonged period of non production such a s long break for lunch as heat can build up then and the temperature become too high.
Any Other Recommendations / Thoughts relating to garment factories dealing with fabrics at production stage?
There is a lot of info above to digest and think about. Plus some of the attachments you may find interesting and want to come back with some more questions so I will leave this here for now.
Frank
Critical Path
Product Activity Chain
Costings Ready Reckoner
Sealing Stages
Production Plan