PUL – This is a fabric (polyester or cotton) that has been coated on one side with a thin film of waterproof plastic (polyurethene).. so PUL stands for PolyUretheneLaminate. Its considered to be “breathable”. Pads with this should be basically waterproof. Some people don’t like this as they feel the pad becomes as sweaty/non-breathable as a disposable pad and others find no sweatiness and can’t tell the difference with a non-waterproofed pad. A lot of people need it to prevent leaks and make them feel secure – even if only on heavy days.
As it is thin itself, and using it requires less absorbent layers (since the pad can’t leak right through), PUL waterproofed pads can generally be a lot thinner than other pads. The polyester version is most commonly used as it is thinner/softer than the cotton version. It can break down over time, and should not be washed with vinegar or chemicals that can damage the waterproofing. You should also be careful of using a hot clothes dryer or iron, as the plastic can melt or warp.
There are many different brands of PUL. Some brands are reportedly more durable than others, however they all should be more than sufficient for the durability in a cloth pad (given a pad is worn at most a couple of times a month), since the fabric is generally designed these days for use in nappies/diapers which are designed to be washed and reused every few days. However what does matter is the fabric that the laminated costing has been applied to. Some PUL is more “slippery” than others and some is more difficult to sew than others. So you may need to try a few brands to find one you like the best.
Other Laminated (PUL-like) fabrics – There are a few fabrics that are very much the same concept of PUL – a fabric with a very thin waterproof coating. Such as “Procare”, “Gore-tex” and others. Procare seems to be a polyester fabric coated with a vinyl coating. Procare is quite a stiff fabric, compared to PUL, so some people don’t like to use it in pads for this reason. These coated fabrics should work much the same way as PUL – but may not be as flexible or breathable.
Synthetic Fleece – Polyester fleeces (Microfleece, polarfleece, blizzard fleece, “anti-pill fleece”) don’t like to hold moisture, so can make a reasonably effective water-resistant layer on the bottom of the pad, depending on how they are made, as the blood tends to stay in the core rather than seeping through it. As the fabric is a more open weave there is more “breathability” than PUL, but its waterproofing is nowhere near as effective as a result. Depending on the particular fabric, it may be leak-resistant for a light flow only, or it may work for heavier flow. The more densely packed the fibres of the fabric are, the better it will be at resisting leaks. So when looking for a fleece for leak-resistance, you want to look for something as dense (tightly packed together) and thick as possible – not just how fluffy the fabric is. It seems that synthetic fleece is getting thinner over the years, so it is getting harder to find suitable fleeces for water-resistance. Some synthetic fleeces will offer little to no leak-protection. It is best to test the leak-resistance before you sew up pads in it, just in case. Some people use fleece as a bottom layer for its non-slip effect, and some use fleece over the PUL for this reason.
Windpro/Polartec – Polartec is a company making dense, thick, high quality synthetic fleeces that are commonly used in cloth pads, “Windpro” is the name for some of their fleece range. Some Polartec fleeces have a “DWR” (“Durable Water Repellency”) coating on them to help make them waterproof, rather than just water-resistant. This coating will wash out over time however.
Wool – The natural option for leak-resistance in a pad is wool….. I don’t know much about using this in waterproofing a pad (I have a couple of wool backed pads, but never made any for myself). Wool will actually absorb a little as well as resist a little. The wool used in pads seems to be a knit (perhaps slightly felted) and can usually be machine washed. It does not need to be lanolised (because you can’t really). Though if you needed to lanolise it, having the wool as a lay-in booster rather than sewn into the pad, would be the best option, as you can’t lanolise the whole pad or it will prevent the pad from absorbing.
Other (not recommended) options
Waterproof table cloth type fabrics – I’ve found from past experience that waterproofed tablecloths do work well, but can have a more crunchy/crackly type of feel, and aren’t very durable. In a longer pad you might be able to actually hear that as you move. Most likely to be PVC, a non-breathable fabric.
Waterproofed mattress protectors – Not really sure how these go, might be thicker than PUL – most likely a PVC or other non-breathable fabric.
Umbrella or shower curtain fabric – I’m not sure of the composition, but I believe it would be a form of nylon – which would be less water resistant than a PVC tablecloth. Since as an umbrella/shower curtain works by the water sliding over the fabric, it’s not really designed to prevent stationary water from seeping through such as you would use it for in a pad. However, it would presumably work much like a store bought nylon, perhaps a little better. Some people use this.
Nylon – “Ripstop” nylon or other forms of thicker nylon fabric are used by some people, though these are less water-resistant than fleece is, so may not offer any leak-protection to you at all. They are thin fabrics and rely on the fact that the fabric itself doesn’t hold moisture and is a tight weave, so the blood is less likely to travel through. You would have to test a particular fabric to see how it performs.
In my humble opinion if you want waterproofing, its best to stick to some type of PUL (there are several different brands of this), as these are generally thin and quiet in a pad and work well. If you are after water-resistance (or refuse to use PUL), then a good quality thick Fleece is probably the best bet.