What is sponged wool?

Lori writes:

While in several fabric shops in the NY garment district, I saw bolts labeled sponged wool. I could feel the difference in the fabric, but was surprised at how different the wools were (various weights, patterns, and actual composition; not all were 100% wool) and yet still were labeled sponged wool. I’m not sure what that means. Since then, I have asked several instructors and experienced seamstresses but no one seems to know. I tried researching but haven’t found it.

What is the process used to sponge wool? What is the advantage? Does it change just the texture or change something else about the fabric (make it stronger)? Are there any limitations in care due to this treatment? Thank you for any help you can give me.

Sponged wool has been pre-treated for shrinkage. How effective the process can be (based on personal experience) is open for debate. Most sponged wool is used in manufacturing because there isn’t an easy way to preshrink lengths of wool like you can in home sewing. You can sponge at home but the difference between industry vs home is that sponging at home is a cold shrink process. In industry, sponging is a heat shrink (steam) process.
There are various kinds of sponging. One type uses a large drum with holes in it, imagine a dryer drum. The fabric is wound around the drum and steam is forced through the holes. Another kind involves a take up on one end and the bolt of fabric on the other. The fabric is unrolled and rolled from one end to the other, along the way passing over a steam pot. One variation is the steam pot followed by a vacuum table which pulls the water out (illustrated above), drying the fabric. Critical in all of these methods is setting machine tension. If the roller motors aren’t calibrated properly, the tension is too high preventing shrinkage. Too lax a tension and the goods on the path can be drenched in the steam pot and be wrinkled on the take up roller.

Sponged wool is a premium product; last I checked, it costs about 20% more per yard. I would be hesitant to say the nicer finish and pile is strictly due to the sponging process because it depends on so many factors, least of which is a side to side comparison although some designers won’t work with any other kind. Because of the premium cost, I would imagine it is better quality goods that are pre-selected for sponging. However, a manufacturer can have any wool sponged after the fact by taking it to someone who does finishing or a laundry (or a dyer even) that specializes in serving the garment trade if they have the equipment. Many wool vendors have relationships and will arrange to have it done for the customer before shipping the goods.

Cold shrinking:
You can use the cold shrink method at home although this process is not likely to raise a nap if you like that look. The process is to drench a bed sheet, fold it in half and lay it out full length on the floor. Lay the wool on top of the sheet starting about two feet down from one end of the sheet. Fold that exposed sheet end onto the wool. Then fold the whole length of goods loosely, the point is to have a layer of wet sheet interlaced with wool. Store put the bundle someplace and let it sit for… I don’t remember how long, until it dries or nearly so. Living in the southwest, I’d likely cover it with plastic to keep it wetter longer, at least a day or so. The last time I did this I was living in Dallas where it is more humid. Don’t make me swear to it but I think a 48 hour period was prescribed.

Lori responded:

I knew I had finally asked the right person! How lovely to know the process and what it does; now wish I had been braver about buying some so I could examine it more closely. There were many at Paron’s in the 50% off room, and I noted that several had a ‘spongy’ feel or almost like a bit of loft. Now I wonder if that was more my imagination in trying to figure out the term.

Your use of ‘imagine a dryer drum’ led me to two other thoughts. Pamela Erny had posted a method of preshrinking wool at home. It strikes me as being a sort of home version of sponging.

Pam’s version is interesting, I haven’t seen that one before. It seems akin to a minimalist process of boiling wool -which is itself, an extreme version of sponging.

Speaking of boiled wool, I don’t know how that is done in industry but I may look it up later. We buy boiled wool as is; I haven’t known of anyone getting regular wool and having it boiled. Which is not to say you can’t do it fairly easily at home. I’ve done it by washing and drying wool repeatedly. It’s pretty hard to mess up but you want to be sure you don’t make the wool brittle by stripping out what remains of the natural oils with detergent and heat. I like to use shampoo (in one cycle) and replenish moisture with hair conditioner for subsequent cycles. Using a hot dryer is fine as long as you do the latter but avoid Johnson & Johnson baby shampoo; it is very astringent.

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  1. Very interesting stuff here. I know that when I felt from wool roving, the shrinking process is called “fulling”, which includes throwing the felt onto a hard surface, and then rubbing it on a rough surface. I’m seems to me that basically 3 things help to further meld the fibers together, whether thats called felting or shrinking, and those are: water, temperature change, and soap.

  2. kay says:

    Typical schedule for London shrink (the sheet method used at home) is “overnight” for holding the fabric damp. Supposedly the name is derived from leaving newly woven Yorkshire wool was unrolled and left to soak up the dew and dry again in Bermondsey Common. As commons were common grazing lands, it strikes me as perhaps not the best place to lay out a bunch of fabric…

  3. Thomas Cunningham says:

    frankly not sure how many spongers are left, in the men’s business at least. There was an outfit somewhere New Bedford, Mass, think they are gone now. Another in PA that closed down a couple of years back. I wouldn’t know where to go to get goods sponged today.

  4. Donna S says:

    Correction to the felting and fulling process. It is heat , water and friction that cause the fibers to shrink and the barbs on the fibers to lock together to form a dense fabric. The process is not reversible.
    Too bad the industry can’t just say pre-shrunk for the sponging process. Less confusing, unless I am misssing something about the process.

  5. Kathleen says:

    Thomas, Forstman’s used to sell it (or have it done) for some of the better 18%-22% wools. Maybe that was something that wasn’t passed on when they were acquired by that Canadian company. Maybe you can still get it in Canada. Things seem to be better made in Canada, nicer finishing.

  6. Lori says:

    I did a little more research on the fabrics I had seen in New York and learned that the vast majority were imported from Italy, with a few from France or England. It’s a shame that it is uncommon in the US now.

  7. Mary Beth says:

    I used to sponge all my lengths of wool before shelving (3 to 20 yards cuts). I’m a home sewist.

    I’ve cold shrunk using the wet sheet with the wool tightly wrapped in it over night, lying the goods out to dry for a few days and I’ve steam shrunk using a high steam iron and lying flat to dry. I also have a home dryer with hot steam and dry function. The dryer with steam and drying function was the least efficacious but that might have been because of the amount of wool being processed at the time, 20 yards.

    I’ve used Pam’s method (which did not full the wool as I expected it would) and it worked perfectly. You still have to have the space to lay flat to dry. Pendleton Woolen Mills (Washougal, Washington) offers “needle ready”, aka “sponged”, wools here in the US but I don’t have a handy retail outlet link and The Wool House in Canada offers “needle ready” goods, usually from Italy, to tailors throughout Canada. I often get needle ready wools from Michael’s Fabrics but since as a retailor, he can’t guarantee this fact he doesn’t claim it.

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