I frequently receive calls from people wanting to know how to full their prefelted alpaca sheets. These are typically sheets of felt made on a table felting machine and they will have a diamond pattern/texture embossed onto the top and bottom of the sheet. These prefelts need to be fulled in order to complete the felting process and ensure that your felt is stable enough to use without pulling apart. One thing to note is frequently, the fiber that is used to make these prefelts is poor quality fiber with mostly guard hair. Either it is the stuff that collects under the other equipment while yarn is being processed or it is the second quality fibers. If this is the case, guard hair does not felt. If there is enough decent fiber to hold it together the guard hair will sort of float on the top and the finished felt will be very "hairy" looking and may not be very strong, depending on the ratio of guard hair to good fiber. If the prefelts are blanket fiber than the following methods will full them into a denser felt that you should be able to use.

Begin by laying your prefelted sheet onto a felting surface that can be rolled up. I use large pieces of industrial strength bubble wrap. Others use a high thread count bed sheet or a grass mat used for sun bathing or window blinds. The key is to have a flexible surface that your fiber will not felt itself to and it should be large enough to extend beyond the felted piece and allow enough extra to get a good wrap.

Wet the prefelted sheet with hot, soapy water, on a large reed mat or sheet of bubble wrap then you roll it up like a big jelly roll, tie the bundle so it can't unroll and then roll it back and forth on the table or floor. You need to use enough soapy water to completely saturate the piece and press all the air pockets out. If you get to much water on, don’t worry, it will come out as soon as you roll it up!

You can roll it up onto a rod or 2"wood dowel running through the center to help it felt faster also.

Depending on the thickness of the felt, the rolling time will vary. Try about 100 times, back and forth the length of your arm for a light weight piece. Then open the bundle and roll it from the opposite direction, tie it up and roll another 100 times. Open the bundle again and roll from the side and repeat the process from both sides. The felt is shrinking in the direction that you are rolling and faster on the inside than on the outside of the roll. If you only roll from one direction then it will harden more at one side. What this all boils down to is it won't be square any more.

Once it is felted all the way through, I put the prefelt in the dryer, sopping wet and let it slam around in there for a while. Usually 3-9 minutes with high heat setting, depending on the fiber and the amount. Some fiber will felt faster than you expect so you need to really watch it at this point. What you are after,  is the slamming motion and heat of the dryer. You are not trying to "dry" the piece. Caution: if your prefelt is made with poor quality fiber, it is going to begin shedding at this point. You may not want to have it do this in your dryer.

If you are not brave enough to do this with your dryer, then you can take it sopping wet, and slam it down on a table or floor. I used to stand over a clean tray and throw it to the ground outside. Or with a table, I'd throw it into the air and let if fall to the table. Either way the soap and water will spatter everywhere. Depending on the size of the piece, I will fold it up or drop it flat and with some pieces I will wad them up. Just depends on the project. If it seems to not be getting hard enough, than you can try adding more HOT soapy water. The hot will open the scales again and encourage better tangling.

I have worked on many prefelts from several different mills and I have found that often, after they are fulled properly, they develop holes in the fabric, or one edge will felt very irregularly. The holes and uneven shrinking can be caused by a number of factors. Usually the carded batts that were used for the felt had thin spots in them that were not apparent until the felt was done. If the fibers are short and the layers are uneven, as the fibers become more tangled, they pull from the thinner areas and congregate in the thicker areas and the next thing you know, there is a hole.

Unfortunately, if you develop holes at the final stages, there is little you can do to fix it but work around them.

Felting is a very simple process that requires a lot of work. If you are going to all the work of making felt, start with good quality fiber and prepare it properly for your project.