by katie  Mar 15, 2019  Blog, Technical Weave
Once you have decided on a project you may want to work out how much yarn you are going to need. This may be so you can buy or dye the correct amount without vastly over or under estimating.
The following will take you through the calculation to work out how much weft yarn will be needed. It looks like a lot but they should be relatively straight forward things to work out. For the sake of simplicity I will work in centimetres/meters but the same can be applied to inches/yards.
The calculaion is as follows:
Total number of picks x total width of fabric (m) = amount of yarn needed (m)
How to work out the total number of picks
 PPC (picks per cm) x (length of woven piece (cm) + shrinkage/takeup (cm)) = Total number of picks
 The picks per cm is usually determined by sampling but if it has no been woven before see CALCULATING A SETT and use the same as the epc.
 The shrinkage/takeup is usually assumed to be 10% of the width of the woven piece but this can vary by a large amount depending on the yarn, structure and finishing. Sampling will give you a more accurate number.
How to work out the total width of the warp
 width of woven piece (m)+ shrinkage/takeup (m) = Total widthof warp (m)
 The shrinkage/takeup is usually assumed to be 10% of the width of the woven piece but this can vary by a large amount depending on the yarn, structure and finishing. Sampling will give you a more accurate number.
 It is often easier to work out the calculations in cm and then convert to m by dividing by 100 at the end.
As a working example:
Total number of picks:
 8 ppcm
 200cm length of woven piece
 10% of 200cm = 20cm shrinkage/takeup
8 x (200 + 20) = 1760 picks
Total width of warp:
 50cm wide woven sample
 10% of 50 = 5cm shinkage/takeup
50 + 5 = 55cm (0.55m)
1760 x 0.55 = 968m of yarn needed for the warp
Calculating warp yarn quantity
Calculating the sett
by katie  Mar 9, 2019  Blog, Technical Weave
Leno is a weave structure where two or more warp threads twist around the weft threads. This technique is often used to create strong, fine fabric which is stable. The twisted warp yarns ensure the yarn does not move. It is also useful to use this ta the edge of a gap in the warp otherwise the warp ends have a tendency to want to fill the space.
Setting up a loom for doup leno is time consuming but once it is set up it’s fairly quick to weave.
To create this structure a loop of thread (a doup) is attached to an empty shaft and travels through an empty heddle on an adjacent shaft. The doup warp end is then threaded through the doup to pull it under an adjacent warp end creating a twist. A weft pick holds the twist in place.
Below shows a doup attached to shaft 2 and poking through an empty heddle on shaft 1. Two shafts are needed to create the twist and two are needed for the twisting warp ends. This is in addition to any shafts needed if other structures are to be included in the fabric. It is important that the doup is not too long and only just reaches through the heddle as this would result in a poor shed. The warp end to be twisted will be threaded through this loop rather than a heddle.
A strong smooth thread works best for the doups. A doup will be needed for every twist required. It’s a good idea to make the doups by tying them around something such as two nails in a piece of wood spaced the required distance apart. They need to all be consistent in length to ensure an even shed.
The direction of the twist can be changed and the number of warp ends which twist around each other can be varied. The following shows a selection of options:
Here is a draft for a weave using doup leno and plain weave structures:
It is important to remember that all the twisting threads (leno ends and warp ends) must be put through the same dent in the reed.
To make it easy to see which warp ends will be twisting these threads are black. All the other threads are white. 8 shafts are used:
Shaft 1 will contain the empty heddle for each doup to be threaded through and will be lifted every time the warp thread is to be twisted.
Shaft 2 is where the doups will be attached .This shaft will need to be kept raised throughout the whole weaving process otherwise the leno warp end may be broken.
Shaft 3 is for the black leno ends which are the ones to be twisted. This will be lowered when shaft 1 is lifted to create the threads.
Shaft 4 it for the warp end that the black end will twist around and remains stationary (lowered) throughout the weaving process.
Shafts 58 are used for the plain weave of the rest of the fabric.
In the draft above there are two sections of Leno on a plain weave fabric. One on the left where just two leno threads are used to stop the warp moving in to a gap in the warp. The second on the right is an area of leno in which two leno ends twist around two warp ends.
Below are close ups of the two different leno weaves from the above draft as well as a diagram for each to show how the dark leno ends are twisitng.
by katie  Oct 28, 2018  Blog, Technical Weave
In an extra weft structure one weft yarn is used to weave a ground cloth and an additional weft is inserted at intervals to create a decorative pattern on the surface on the cloth.
The ground cloth is usually woven with a simple structure such as a plain or twill weave to enhance the extra weft but other structures can be used.
The sections of the warp that will interact with the extra warp to create the pattern are set up on separate shafts to allow it to be woven independently from the ground cloth where required. The number of shafts needed depends on how complicated the pattern is going to be.
For the example below I have used an eight shaft loom. Plain weave is woven across all 8 shafts for the ground cloth (block A and B woven simultaneously). Shafts 58 (block B) are only threaded in specific areas and are woven independently to create diamonds at regular intervals throughout the cloth.
The first end in block A after a block of B must be threaded on shaft two otherwise a plain weave structure will not be possible. The best way to spot these potential errors before weaving is to draw out the draft either by hand or on a weave program.
Below is the weave draft showing how a diamond structure can be achieved using an extra weft structure:
To ensure a stable structure around the extra weft diamond, the ground cloth picks are alternated with the extra weft picks. On the left of the draft the filled circles represent the extra weft and the empty one the weft represent the ground cloth.
This is how the blocks will be spread throughout the woven sample:
Where there are three diamonds placed right next to each other I have placed one warp end separating them, threaded on shaft two. If they were not separated by this thread there would be one weft pick floating over the middle of all three diamonds. Threading plan for the three diamonds next to each other:
The woven samples below are all woven with the same warp set up. Included is the diamond structure explained above.
Extra weft structures can be used in many different ways to create a vast range of cloths.
by katie  May 30, 2018  Blog, Technical Weave
Once you have decided on a project you may want to work out how much yarn you are going to need. This may be so you can buy or dye the correct amount without vastly over or under estimating.
The following will take you through the calculation to do this. It looks like a lot but they should be relatively straight forward things to work out. For the sake of simplicity I will work in centimetres/meters but the same can be applied to inches/yards.
The calculaion is as follows:
Total number of ends x total length of warp (m) = amount of yarn needed (m)
How to work out the total number of ends
 EPC (see calculating sett) x (width of woven piece (cm) + shrinkage/takeup (cm)) = Total number of ends
 The shrinkage/takeup is usually assumed to be 10% of the width of the woven piece but this can vary by a large amount depending on the yarn, structure and finishing. Sampling will give you a more accurate number.
How to work out the total length of the warp
 Length of woven piece(s) (m)+ shrinkage/takeup (m) + yarn wastage (m) = Total length of warp (m)
 If weaving more than one piece add the lengths together
 The shrinkage/takeup is usually assumed to be 10% of the length of the woven piece but this can vary by a large amount depending on the yarn, structure and finishing. Sampling will give you a more accurate number.
 Yarn wastage is the amount of yarn used to tie on to the front beam plus the warp woven for even end distribution plus the loom waste (the amount of yarn left on the loom not able to be woven).
 It is often easier to work out the calculations in cm and then convert to m by dividing by 100 at the end.
As a working example:
Total number of ends:
 8 EPC
 50cm wide warp
 10% of 50cm = 5cm shrinkage/takeup
8 x (50 + 5) = 440 ends
Total length of warp:
 Three 50cm woven pieces = 150cm
 10% of 150 = 15cm shinkage/takeup
 10cm to tie on
 5cm to weave distributing picks
 50cm left on the loom that cant be woven
150 + 15 + 10 + 5 + 50 = 228cm (2.28m)
440 x 2.28 = 1003.2m of yarn needed for the warp
Calculating the sett
by katie  Apr 26, 2018  Blog, Technical Weave
What is a sett?
Once you have chosen a yarn(s) to use use for a warp you need to consider the sett. In other words, the number of warp ends you will want to have in your woven cloth per centimetre/inch (ends per centimetre (EPC) or ends per inch (EPI)).
Things that may affect the sett
There are a number of factors that need to be taken in to consideration and may affect the sett you choose:
Weave structure
A weave structure with fewer weft intersections with the warp will require a higher sett. For example a 3/1 twill will require a higher sett than a plain weave.
Final use/aesthetics of the fabric
If the final outcome is to be a lightweight scarf then the sett may need to reduced considerably. On the other hand if the fabric is to be cut and sewn a much higher sett is needed so it holds together well. A higher sett will also make it harder wearing.
Personal preference
Some weavers prefer to use a slightly higher/lower EPC/EPI and may also beat down their weft harder/more softly.
Bearing this in mind the below is only a guide and other factors will affect the sett.
How to work out the sett
To work this out you need to take your yarn and wrap it around a ruler. Do this with no gaps between but ensure the yarn does not bunch up or overlap. Wrap it around in a 1 cm or 1″ section as shown below.
Dividing the number of times the yarn was wrapped by 2 gives you the EPC/EPI of your woven cloth.
This method is usually a good indicator of the number of ends you will need for a balanced plain weave structure. When we talk about a balanced plain weave we mean a plain weave where the warp and weft are equally visible, neither one dominates the other.
For a balanced twill you would use 2/3 of the number of ends round the ruler.
In the photo above the yarn was wrapped around the ruler 14 times within 1cm. This means I would want to start with 7 EPC for a plain weave or 10 EPC for a twill.
If different structures are to be woven then the EPC/EPI will need to be adjusted. There is a formula to work this out mathematically which can be confusing. It may also be affected by previously mentioned variables which cannot be taken into consideration with a formula. The formula is as follows:
S= T X R
bn(I + R)
S is the sett.
T is the number of times the yarn was wrapped around a ruler.
R is how many ends there are in one repeat.
I is the number of weft intersections in one repeat.
I personally prefer to use the first method mentioned and adjust it taking all other aspects of the woven piece in to consideration. Sampling really is the only way to get just the right sett.
by katie  Apr 8, 2018  Blog, Technical Weave
Yarn is made from a variety of different fibres and it is important to have an understanding of where these fibres come from. The following table show some of the most common types and their origin:
Fibre type 
Yarn 
Origin 
Natural (cellulose)

Cotton 
White boll which surrounds the seed of the cotton plant 
Flax/linen 
Filament fibre from flax plants 
Hemp 
Hemp plant (a Angiosperm phylum) 
Jute 
Corchorus olitorius plant 
Ramie 
Bark of Boehmeria nivea 
Sisal 
Leaf of the Agave sisalana plant 
Bamboo 
Stem of the bamboo plant 
Paper 
Wood pulp 
Abaca 
Leaf of the banana plant 
Banana 
Stem of the banana plant 
Pineapple 
Leaf of pineapple plant 
Coir 
Husk of the coconut fruit 
Lyocel (tencel) 
Wood pulp 
Seacell 
Wood pulp and seaweed (algae) 
Natural (protein)

Sheep wool 
Sheep hair 
Alpaca 
Alpaca hair 
Cashmere 
Cashmere goat 
Mohair 
Angora goat 
Angora rabbit 
Angora rabbit 
Camel 
Camel hair 
Horse 
Horse hair 
Lama 
Lama hair 
Mulberry Silk 
Silkworm cocoons 
Tussah silk 
Tussah silk moth cocoon 
Synthetic

Vicsose 
Wood pulp 
Rayon 
Cellulose from a variety of plants 
Polyester 
Synthetic resin 
Elastane 
Minimum of 85% polyurethane polymer 
Acrylic 
Minimum of 85% acrylonitrile monomer 
Some fibres come from a natural source but are classed as synthetic. This is due to the manufacturing process the fibre has gone through to and whether the end fibre is biodegradable.