Hot Cutting Fabric

I’m not sure what the best name for this is – heat cutting, hot knife, hot cutting – but the idea is simple: Cut synthetic fabric and seal the edge at the same time. If anyone has been caught sitting a bit too close to a fire in some nice nylon pants and gotten a spark on them, you would know that the pants didn’t burn or smoulder, but they quickly and efficiently melted in the exact place where the heat made contact. It is this property that allows us to use a hot knife (or in my case a soldering iron) to essentially melt the fabric as if cutting it with scissors. Once the cut is made, all of the raw edges are seared and won’t fray.

I’ve worked on two projects using this cutting method, each with fabric on opposite ends of the synthetic spectrum. The first was the chalk bucket, using 1000D Cordura, and the second was a pillow cover, using 30D nylon (which will hopefully be a post soon). I’ve learned a couple of things, and I thought I would share it.

First are the pieces needed. The two things I am using are a pane of glass measuring 30″x36″ and a soldering iron purchased from the local Home Depot. The total cost is about $35, give or take. It isn’t the cheapest way to cut fabric, but if you are dealing with lightweight synthetic fabrics on a regular basis, and I would say most UL MYOGers are, it can be worth it. The soldering iron comes with a few tips, but one of them comes to a nice point and works well for cutting. It is hot enough to cut through even the 1000D with just two pretty easy strokes. The glass is meant to give a heat resistance surface to cut on to protect your table. The combination works very nicely together. One other thing I use is a wetted sponge, to help clean the tip of the iron.

tools
Tools shown ready for cutting. I have the sponge for cleaning the tip, the soldering iron ready to go on the mount, my fabric held down by water bottles, which just helps a bit, all on top of the pane of glass (which I keep the cardboard backing for)

Another tool I am regularly using is a 12″x8″ metal carpenter’s square. What I have found is that with heavy fabrics you can free hand just about any shape you want while cutting. However, with 30D fabric, cutting along the length of the ruler is the safe bet. With some practice, I think free handing it will be possible with lightweight fabric, but using the ruler was very quick and efficient. By getting a metal one, you can have the tip of the soldering iron right next to the ruler and not worry about accidentally getting more than you meant. By getting one with a right angle, measurements are easier to make, and you can also use it for cutting corners out like the below.

corner_cut

Another tip I can give is that if you need to cut a segment longer than your ruler, you should cut it, then peel is back before moving the ruler. This way the cut line stays consistent, and you will know if there are any spots that you missed or melted, then meshed back together, which can indeed happen.

cutting

One important thing to remember is that the iron is hot – hopefully 900 degrees if the box tells it true. So this is a bit more dangerous than cutting fabric with scissors. There is always the possibility of melting fabric you didn’t mean to or burning yourself. Be sure to treat the iron with respect. Oh, and it is best to keep a window open to let everything air out.

I gain two benefits from hot cutting over scissors. The first is efficiency. This may be a perceived benefit, but my cutting goes about much more quickly while hot cutting for some reason. The second, and more important, is that my pieces no longer fray as I try to sew up my project. With some fabrics it seems like a race to complete the project before I lose an inch of fabric. But once the fabric is heat sealed, it won’t fray (as easily) and gives me time to work methodically on my project.

I think this was a good purchase for future projects, and I am excited to keep trying it out. I’ll be sure to update the blog if I learn anything important as I go.

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6 thoughts on “Hot Cutting Fabric

  1. I use a 3/4″ by 1/2″ L-shaped or angle aluminum stock. It can be bought at Ace Hardware of wherever. The length is maybe 24″. It can be cut to whatever length you like, of course. The angle gives me a place to rest my finger tips as I run the iron along the edge to cut the material. I also use a clear ‘sewing ruler’ It is 3″ wide and 18″ long. There are various sizes. Because it is clear, it is pretty easy to mark up boxes and triangles with chalk or whatever you prefer.

    1. I really like the idea of the aluminum stock. I am thinking about cutting out some circular and arced pieces of lightweight fabric for reinforcements, and I may go buy some cheap aluminum sheets from Home Depot to cut out of the shapes I need for hot cutting them. That way, it won’t have to be free handed.

      I know the exact type of sewing ruler you are using. Does it stand up to the heat well?

      1. The sewing ruler is just a type that you can buy at JoAnn’s or where ever. I only use it for marking up. I don’t run the iron along it. The iron only goes against the aluminum.

        I have troubles cutting arcs as well. Recently, I ran across a tip to use poster board… I haven’t tries it and I think I would have to use a light hand in order to not jump the tip over the thin edge of the poster board. The aluminum jig would last forever but I think the poster board would be much easier to form. Not much in cost to test it out, either.

        Now that I think about it, I haven’t seen any aluminum plate in the form of circles. It would sometimes be useful to have a circle of 4 or 6 or whatever inches diameter to cut simple arcs. There may be something in hardware plumbing sections that may be useful. I don’t know if any of the plastics there are heat resistant enough to run the iron along quickly. I would have to ask…

        Sorry for the late reply. However, the late reply gave time for these posts, linked below, to be made. Look toward the bottom for Peter. I am Tan68 there.

        http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=41535&startat=80

        He mentions that heat will be drawn from the tip by the aluminum. This is true, but I haven’t ever had a problem. I have to reposition my material often so the iron warms up again.

  2. What kind of a soldering iron do you use? I know nothing about them. There appears to be a lot of them. How hot should it be? Is there one you could recommend? Thanks!

      1. Wow! You are awesome! I just heard from Margaret Beal, the textile artist in the UK. She has a book out on how to use the soldering irons. I guess she pioneered the technique for quilters. Her work is awesome. She has one that is specially made for her and she sells them, too. But, I like what you have suggested, as it is going to be less expensive. I am not a quilter. I just want to cut out shapes for grand-daughters barrettes and headbands. Thank you, so much!

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