Adjusting Thread Density for Different Thread Types and Effects

Setting the correct density for an embroidered design is a fundamental part of digitizing and creating well executed designs. The term "density" refers to the distance between the individual threads that make up the stitches, regardless of the stitch type. Within your digitizing software, the density is calculated either by units based on 1/10th of a millimeter, or units of a millimeter. For example, if calculated by 1/10th of a millimeter, the density of 4 appears as 0.40mm. If based on one millimeter, it is inserted as 4.0mm. Either way, it is calculated as 4 units.

"Ramping" is another automatic setting that works in the background of the digitizing software. This works as a fine tuning to increase or decrease density based on the width of the shape you are embroidering. For example, if you have a satin stitch that is 4 mm wide, then becomes 2 mm wide, and then, at its widest point, is 8mm wide, the ramp can be set up so that when the width of the shape is 4 mm, the density will be set with 4 units. As the shape narrows down to 2 mm wide, the density will reduce by 7%, and where its width increases up to 8 mm, the density will become heavier by 5%.

This decrease in the smaller widths helps prevent an over crowding of stitches because there is not as much movement between the threads in the smaller widths. The increase of density in the wider portion is to compensate for the movement of threads, since there is more space for the thread to move. This is just an example of one ramp setting. In most digitizing software there are different default ramp settings to choose from. In most software, this ramp default setting can be adjusted to the embroiderer's personal preference. The type of ramp setting you choose will be based on the thread type, the thickness and also the fabric to be embroidered. Most beginner embroiderers will stay with the default setting until they understand how to set densities and appreciate the effect they have on the digitized design and its substrate.

Setting the correct density depends on:

• Thread type and thickness of the thread being used.
• The type of fabric that the design is to be sewn on.
• The creation of special effects.

Thread Type and Thread Thickness
Embroidery threads come in a variety of thicknesses and types. The standard, general use embroidery thread has a thickness, or weight, of Number 40. The most popular thread types are 100% viscose rayon and 100% polyester. The average density setting for a 40 weight thread is 4 units. From this value a digitizer has a base to work from, in order to set densities for other thread thicknesses. The thicker the thread is, the higher the unit numbers should be set, creating a larger distance between the threads. For example, for a Number 30 weight thread the density is set at 5 units. The thinner the thread is, the lower the unit number becomes, so that the density for a Number 60 weight thread would be set to 3.5 units.

The chart below lists the density settings for general purpose and some specialty threads. This list of density settings is meant as a starting point. The densities that are listed are meant to provide full coverage of the material. The density settings may have to be adjusted slightly, depending on the style of artwork, type of stitches and the fabric that is being used.

Recommended Densities for Various Thread Weights

Special threads such as the Smooth Metallic Number 40 may need a lesser density than the standard Number 40 rayon or polyester. This is because of the construction of the metallic thread, which tends not to lay as flat as standard embroidery threads because of its metal fibers. Designs that have small details, or when embroidering on thin satins, may require more distance set between the stitches. If the density units are set too heavy, the thread will tend to break during the embroidery production. If this occurs, try lightening up the density. In most cases, this will correct the problem.

Effect of Fabric Type on Density
There are three basic types of fabric construction: knit, woven and non-woven. Within these three types there are many variations. Some lightweight woven fabrics have a tendency to pucker when embroidered. Even though it may be very stable because of the woven construction, the fabric cannot absorb very dense stitches very well. However, the style and size of the design also play an important role in determining density settings. In some cases, lightening the density by about 5% can prevent or decrease the puckering.
On the other hand, increasing the density of the top stitching won't solve every problem, as is the case with knitted fabrics which tend to "absorb" the stitching. When embroidering on knit fabric, you have to create underlay stitches that will stabilize the fabric for the top stitching. Here, the underlay density can be adjusted to hold up the stitches on top of the fabric, so that they do not fall into the structure of the fibers of the fabric.

With non-woven fabrics like leather, the density units should not be set too heavy, because an increase of density will make the needle perforate the fabric, weakening its structure and causing the design to nearly be lifted out, like a cookie cutter, and damage the leather.

The Creation of Special Effects
The digitizer can create effects like shading, color blending and other optical illusions by different density settings. When creating a color blend with two thread colors, one must be placed on top of the other. The density will have to be lightened in the section where the two colors overlap. In some digitizing software systems, this may be set as a special feature, which will do this automatically with a few adjustments by the digitizer.

To blend a color from light blue to dark blue, for example, you may need more than two thread colors and many density changes in order to create the blend effect. Another way of blending with two colors is to digitize the first color with a normal density of 4 units if using a standard thread, and then digitizing the second color with a density that changes its units from 20 to 4 units and then back to 20 units, as shown in Picture 1 and 2. This "accordion effect" can be achieved with a special feature within the digitizing software system.

Picture 1: Normal Density of 4 units

Picture 2: Density of 20 to 4 to 20 units

In picture 2 you can see the accordion effect -- the threads are wider apart, then move closer together and then widen again. This accordion effect creates the illusion of color changing between two colors. It is important that the stitch directions are placed at the same angle in order for the thread to blend into one another.

Another technique of blending thread colors is the use of fill stitching with a very open density, for example, using units of 20 to 30, overlapping each other at various angles. This type of stitching will allow the background fabric color and texture to play a part in the color blending effect.

Picture 3 Showing open fill technique

Creating any kind of color blending will take a bit of practice, like everything else in embroidery. Mastering the effects of density with different thread types and thread weights, and becoming comfortable with different specialty threads, can open up doors, making your embroidery design work stand apart from the competition.

Born in the U.S., designer/digitizer Bonnie Nielsen works in the Freiburg, Germany, headquarters of embroidery thread manufacturer Madeira. Bonnie has distinguished herself internationally with her embroidered art pieces and articles that appear in the international professional garment and embroidery magazines, such as Eurostitch. Madeira utilizes Bonnie's expertise to work on special projects that include educating embroiderers on technique and working with specialty thread.

Madeira Special for Professional Embroiderers:
Shade kits are available at a special price for you! Get a 32-spool shade kit for $52, which is over $6 saving. Please note: The Special Effects Collection is specially priced for you at $59.65. Go to www.madeirausa.com, click on thread, and choose Kits in the Polyneon #40 section to see the thread colors available. There are 11 kits with 32 spools each; each spool contains 1,100 yards. Please use Code NEC129 when ordering to secure your special price.

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