I've had a few conversations recently with fellow artists/crafters about the different types of felting, what's involved, etc. After all, while the end result to some degree is the same (you get an object made of matted down/interlocked wool and/or other fibers called felt), the processes are vastly different. I thought maybe I would help to clear all that up :) Before I go on, felting IS violent. It's the perfect art for getting your aggression out. It just depends on if your aggression is more of the fighting kind or the "Psycho" kind.
Most of my readers on this blog I would assume to be needle felters, since that's pretty much all I talk about.
Needle felting is the use of a thin, barbed needle to entangle and lock the fibers into place. It allows the felter to use a wide variety of fibers, as needle felting is not as dependent on the scales found on protein fibers as it is in the process of entangling the fibers, so one can use plant or even man-made fibers in addition to animal fibers.
It is also the most portable of all felting styles as it does not require access to water or a large surface area to lay out one's work. It is a process that can be done in bed, in the car, while sitting on the couch watching TV, at the park, etc. This portability is especially beneficial to those who enjoy sketching/painting en plain air, as they can bring their wool roving and surface with them, set a rigid foam up on a sturdy easel and essentially replicate the process.
This is also a process that does not require much physical energy or strength beyond that of the ability to hold the needle and stab repeatedly - so it may be more difficult for someone with CTS or arthritis - however there are certain needle holder tools that allows the felter to use the whole hand to hold the needle, easing the felting process. If you do not wish to purchase a tool but would like to make it easier to hold via your whole hand, I once read you can use a palm-sized felt ball, stabbing the needle through that, and the felt ball can work as your needle holder. This would also work for young children who are ready to start felting but still need to build up their hand strength/dexterity. In some ways needle felting is more time consuming, but in others it is far more versatile. Ultimately, although one can use a combination of techniques to reach a desired result, it is very easy to tell apart something that has been needle felted vs something that is entirely wet felted. Needle felting is mostly used in 3-dimensional sculptural items, however it can also be used for wool paintings, embellishments, and even creating fairly 2-dimentional textiles (commercial felt is created with giant, wide felting machines that have hundreds of needles across punching the fiber into a thin textile), however for the individual felter wishing to create a 2-d textile, wet felting is a much more efficient process, not to mention you're not left with poke holes from the needle.
Wet felting involves the use of hot water and often some form of soap (though not required) to open up the scales on a protein fiber, and through the process of agitation forcing the fibers to interlock. It is often combined with shocking the fibers (using cold water) causing the scales of the protein fibers to close back up and the fiber to crimp up, thus shrinking the final item down further. It is a very energy-intensive process, using one's whole body in order to agitate, roll, throw, shock, etc., really allowing the felter to take out any and all aggression on their art to make something beautiful. To be honest, both wet felting and needle felting are rather aggressive forms of art, it's just that needle felting is more like Hitchcock's "Psycho" and wet felting is more like kung fu fighting. The end result is also rather different between the two, as wet felted items have a much smoother finish and is mostly used in textile-type art (think scarves, hats, wool paintings, clothing items, shoes). Traditionally it was also used to create felt rugs and even yurt coverings, however the tribes which practiced these traditional crafts are quickly becoming modernized. Within the scope of wet felting, we have a few additional processes, but wet felting in and of itself just involves criss-crossing protein fibers, getting them wet with a solution of soap and hot water and gently agitating until it holds together. When you reach the point where it's held together, pinching it to check that it's not falling apart, that's when you really take your anger out on it. Once the felter gets beyond just the scope of wet felting and starts experimenting with texture and a variety of techniques, that's where the real magic happens. Just as I've seen some amazing things created with needle felting that could not be replicated with any other medium or process, I can say the same about wet felting. Some of my most favorite, sculptural felt installations were in fact wet felted.
All nuno felting means is wet felting with fabric. Instead of simply having protein fibers felting onto itself, you add a fabric to the mix, into which the fibers go in and out between the woven fibers and then felt with each other on both sides. Pretty much any fabric can be used, however the process is more painstaking and involved depending on the fabric you choose. Popular choices include silks, linens, any open-weave fabrics. You can also use pre-felt (however felt itself is incredibly difficult to nuno felt). The looser the weave, the easier to nuno-felt. Unlike wet felting where you first start by rubbing, with nuno felting you start by pressing to make sure the fibers make it through the fabric. If you skip this step and proceed straight to agitating, all you will end up doing is felting the fibers on top of the fabric, and you'll be able to tear the felt off the material.
This is what most people are most familiar with when it comes to felting, especially since crocheting and knitting has a much wider base of artisans. In fact, anyone who has ever accidentally shrunk a sweater in the dryer has felted. If you are familiar with either craft, all you need to do is knit or crochet something out of a protein fiber such as wool, then proceed with wet felting it as either mentioned above or by throwing the item in a hot wash and then dryer. It needs to be wool or another protein fiber, because man-made fibers (such as acrylic) will not felt. Not only that, but you also need to be sure that it is not superwash wool yarn. Superwash yarn is either treated with an acid bath to remove the scales naturally present on protein fibers, thus discouraging it from locking with the fibers around it, and/or it is coated with a polymer or resin to keep it smooth. Superwash is great for making sweaters that you want to ensure will not shrink down when it's washed, but it will leave you cursing your project that you intentionally created with felting in mind.
This is a fairly new technique on the market and not very well known. Artfelt is a type of paper very much like a dissolvable interfacing; however, while dissolvable interfacing will fall apart once any water touches it, artfelt will only dissolve with boiling water. Artfelt combines the process of needle felting and wet felting, using the dryer to handle the agitation process, making this an incredibly easy form of felting. The con to artfelt is that it's one more thing you have to purchase, but the prices are not too unreasonable, coming to around $9/yard if you purchase a 5ftx10ft sheet for $45. I am curious about this so-called artfelt tackboard, as they claim it is self-healing, when it looks exactly like packing foam that I've used in the past that is definitely not self-healing. I'm sure any needle-felting foam you've used thus far would be more than sufficient for your project if you choose to explore this technique. There are a number of kits available to try as well if you need a bit of direction.