Cotton – This is easy to find, and inexpensive – which makes it a popular choice. However it is less absorbent than some other fabrics, which means you may need to use more layers – which may end up more expensive in the end, and can lead to a bulkier pad than if other more absorbent fabrics were used.
Flannel/Flannelette – This is a really thin fabric – what you find fluffy sheets or PJs made of. Not very absorbent on its own, but when you use several layers together you increase the absorbency. Generally used in pantyliners where you need less absorbency. Some people make pads from several layers of this instead of other fabrics, as it is easy to get and can be thinner than cotton terry – however 2-3 layers of flannel might not be as absorbent as one layer of something else, so adding more layers of flannel instead of fewer layers of something more absorbent might not end up being good economy, and is certainly more cutting. The term “Flannel” in the US is the same as the term “Flannelette” in Aus & UK.
Cotton Terry – This term is usually used to refer to the cotton “towelling’ (like you would find towels and wash cloths made from). Cotton terry is quite absorbent, but less absorbent than hemp, and usually more bulky than hemp. Obviously the thicker the terry, the more absorbent it will be – so when choosing a terry, if you want maximum absorbency, pick a nice thick terry.
“Terry Towelling” – This term can also refer to the polyester loopy thin fabric you might find made into tracksuits or baby clothes (think 70s era). This would very rarely be made into pads however and would be a top layer if it was. A polyester terry towelling shouldn’t be used as a core….but I wanted to mention it here, to avoid any confusion.
Burley knit terry (BKT) – To be honest, I don’t know much about this. It is apparently much like Terry, but with thicker loops and is stretchy (so perhaps more like a lush “Terry towelling”). It isn’t often used.
Sherpa – This is hard to describe but if you cross sheepskin and polar fleece… its sort of like that! The fluffy fibres clump together more like a sheepskin does. Not often used as an internal core, more often it is used as a top, but it can be used as a core because it is absorbent.
Cotton Fleece – A fabric with one smooth side and the other is fluffy – almost like polar fleece, but not as fluffy. Thinner than Hemp fleece. Not often used as it can be difficult to find in stores. Lunapads uses this, and it is a fabric commonly found in baby blankets and other such products.
.Hemp – This is generally a hemp cotton blend (50% hemp, 45% cotton). Hemp is reportedly about 2-3 times more absorbent than cotton, yet the hemp fleece/terry most commonly used is quite a compact weave compared to a cotton terry, so this can make for a more absorbent core for less bulk than cotton terry. It’s also commonly reported to be antibacterial, though this is apparently in the oils and looses it over time as the oils wash out – and does not mean that a pad made with this fabric will be in any way, antibacterial. Hemp is the most eco-friendly fabric to use, as it is very durable and highly absorbent – while being a plant that requires no pesticides, little water and does not negatively impact the land is is grown on. While not generally “organic” it is probably more eco-friendly than an organic cotton. However the downside of hemp is that it can get stiff through washing. I have found that washing with “soapnuts” instead of regular detergent keeps hemp feeling nice and soft.
Hemp French Terry – A thin looped fabric, not like the cotton towelling you find in towels, the hemp terry loops are shorter and its generally only on one side (the other is smooth).
Hemp Fleece – A fabric with one smooth side and the other is fluffy – almost like polar fleece, but not as fluffy. Apparently it is made from hemp terry that has been brushed to make the loops break up and become fluffy. It often feels thicker than hemp terry (because of the fluffiness), even if they are the same weight. For a pad core, it shouldn’t matter if you use a hemp terry or hemp fleece as the core.
.Bamboo – Bamboo as a fabric is more absorbent than cotton or hemp and much softer… it also has a slightly shiny look. There is some debate about whether bamboo fabric is very eco-friendly or not. The bamboo plant is very eco-friendly, but usually the process of turning it into fabric does require a far more chemically intense process than turning cotton or hemp into fabric. Bamboo fabrics generally have some cotton component, as bamboo is less durable than cotton – so the cotton adds extra stability to the fabric.
Bamboo Fleece – The usual choice for making pad cores. Generally this fabric is around 70% bamboo and 30% cotton. The cotton component can be organic or not. Organic Bamboo itself is less common. Bamboo fleece is commonly abbreviated as “OBF”, meaning “Organic Bamboo Fleece” – Personally I find the term “organic bamboo fleece” to be misleading, since it is usually the 30% cotton component of the fabric that is organic and not the 70% bamboo component. So the majority of the fabric isn’t organic. As well as there are people who simply call all Bamboo Fleece “OBF” regardless of whether there is organic fabric in there or not. There are different weights of Bamboo Fleece, and these weights are measured in “grams per square metre” (gsm). So obviously the higher the gsm, the thicker and more absorbent your bamboo fleece will be. Anything above 400gsm bamboo fleece is often referred to as “SHOBF” (Super Heavyweight Organic Bamboo Fleece).
Bamboo Terry – Not very common, but it is a loopy fabric, like the terry fabric used for making towels – only a lot softer and more absorbent. Available in a single or double sided terry.
.Synthetics – Some people like to use natural fibres in their pads as much as possible, as they are more natural and breathable. However there are 2 main highly absorbent fabrics that can be used in padmaking.
Microfibre/Microterry – This is commonly used in household cleaning cloths. It reportedly holds around 7 times its weight in liquid, making it a very absorbent fabric while being quite thin. It can however take a long time to fully dry if made into a core of several layers. It can also act a little like a sponge, in that when the fabric is full of liquid, pressing it will allow the liquid to pool (Called “Compression leaking”). For this reason it is best to layer this with a natural fibre to help prevent this.
Zorb – This is a specialty fabric, that is a natural/synthetic blend. Designed for cloth nappies/diapers. It is made from “An optimum blend of cellulosic fibers from cotton/tencel/bamboo/other interspersed with polyester nylon“. It is is highly absorbent and thin – while also being fast drying. The original Zorb 1 is a felt-like fabric, which can shred in the wash and is recommended to be sandwiched between layers of flannel or other fabric, to keep it together. Zorb 1 does not need prewashing. Zorb 2 is already quilted between 2 layers of fabric, but can shrink with the first wash, so is recommended for prewashing before you cut and sew with it. Both zorb fabrics can have compression leaks (where the fabric will allow liquid to pool when the fabric is fully saturated) – so it is recommended to layer zorb with a natural fibre to help prevent this. Often people combine 1 layer of hemp/bamboo/cotton fleece or terry with zorb layers.