All About Bag Interfacing

This post is part of Purse Palooza 2012.

For full schedule of guest post pattern reviews and prizes, click here!

Purse Palooza 2012 is beginning next week, on June 4th! Are you prepared?! Get ready and get set to go with this helpful post on everything bag interfacing!

Today, I have the pleasure of talking about one of my most favorite things in the world...interfacing! This post will be concentrated on the particular Pellon Interfacings that I use while making bags. Interfacing makes up 25% of my stash...no lie! It's one of those things that you just need to have on hand at all times, because you'll use it in most any project - to make quilted items, bags, garments, you name it!

Pellon interfacing is available in the U.S. If you are one of my friends in another country, I have put together this helpful interfacing conversion chart for Vilene interfacing that you might use when making a bag. For the purpose of this article, I will refer to particular Pellon interfacings, but feel free to glance at the chart to note the interfacing available in your area.

Pellon Interfacing	Vilene Conversion
987F Fusible Fleece	H630 Iron On Lightweight Fleece
TP971F Fusible Thermolam	H640 Iron On High Loft Fleece or 272 Thermolam
SF-101 Shape Flex Fusible Woven	G700 Woven Fusible
520 Deco-Fuse Firm	S520 Firm Interlining
70 Peltex Sew-in	S80 Heavy Sew-in
71F Peltex Single-sided Fusible	S520 Firm Iron-on
809 Decor Bond	H250 Iron-on

I assembled this chart with the help of the lovely folks at Pellon.

So let's get started! Note: always use a pressing cloth when fusing your interfacing to fabric! Pellon interfacing is also available in boxes of product, usually around 2-3 yards per box. You can see examples of boxed interfacing in my photo above; most specialty quilt shops will stock the packaged interfacing!

Pellon 987F Fusible Fleece

Pellon 987F Fusible Fleece can be found by-the-yard at your local fabric store packaged on a bolt with a pale green label on it. It is fusible on one side, which means you can feel the 'glue' on one side, and this is the side that should go against the wrong side of your fabric. This interfacing has a bit of a loft to it. I like using it, but usually reserve it for either the lining of a bag (to add extra body), for straps (so that they are padded, but without any extra bulk), for small flaps, etc. I don't often use it for the exterior of a bag because I have found that over a large area, it can possibly make the fabric look slightly crinkly because of the loft of the fleece.

One way that you can smooth out your fabric when using fusible fleece is to first fuse a layer of Shape Flex (which I'll talk about later) to the fabric, then follow it with a layer of fusible fleece.

Another great use for fusible fleece is that you can cut small squares of it (approximately 2" x 2") to reinforce a magnetic snap that you might be using in your bag. Every time you open and close a magnetic snap, it puts pressure on your fabric. To resist against everyday wear-and-tear, slide the prongs of your snap through your fabric, and then put the square of fleece on top before you close the prongs. You shouldn't have any worries about your fabric tearing under the strain of the magnetic snap now!


Pellon TP971F Fusible Thermolam

Exterior of bag: Pellon 520 and Thermolam - Interior and Straps: Fusible Fleece

I absolutely love Thermolam. It also comes on a bolt with a light green label on it. It is also fusible on one side, so the tacky side should go against the wrong side of the fabric. Thermolam is fleece, but it is a needled fleece, which means it is denser and lies flat. It has a ton of uses. If I'm making a smaller quilted project like a mini quilt, mug rug, or oven mitts, I use Thermolam before I quilt the project. It eliminates the need for using pins or spray baster.

But this article is for bag-making. When I'm making a bag or other accessory, I like it to have body. Even if I was making a simple tote bag, I would not be happy if it was just 2 layers of fabric. Just too thin for me. I know it boils down to personal preference, but if I make a bag, I want it to be able to carry 20lb. without tearing at the bottom. It needs to feel like it has some substance to it.

So, if I am making a soft bag, I always always use Thermolam. I would, say, use the Thermolam fused to the exterior fabric of the bag, and possibly either Shape Flex or fusible fleece fused to the lining fabric of the bag. Thermolam, once fused, will make your fabric look nice and smooth. Depending on your iron, you might need to fuse it for a little bit longer than the manufacturer instructions (I'd suggest testing on a small piece first if you've never used it before). I find I sometimes need to iron it up to double the time as directed. Another personal tip is that I like to iron it (misting with a bit of water) with the interfacing side toward my iron, and when I'm sure it's properly fused, I like to flip it over and iron on top of the fabric (with my pressing cloth in place, of course!). This will give your fabric an incredibly flat and smooth look.


Pellon SF-101 Shape Flex Fusible Woven

I use this in 100% of my bags. I might use it in different ways, but bar none, it is the most important interfacing in my stash. I fuse Shape Flex to every single pocket that I make. I fuse it to facings in garments. I for sure fuse it to an area around a zipper to help reinforce that area. You can find this interfacing in your local shop with a light purple label on the bolt.

Shape Flex will make a quilt-weight cotton have the feel, once fused, of a decor-weight or canvas-weight fabric. It will give the fabric a bit of sturdiness. As with the previous interfacings, the rough tacky side should go against the wrong side of your fabric before ironing. It is perfect as a stand-alone interfacing if you are making a small pouch or other smaller accessory. You can even combine it with other interfacings. Someone asked me the other day what is the most interfacing I have used on one piece of fabric, and the answer is 3. I like to experiment a lot, and there is no right or wrong answer. I might use a layer of Shape Flex, one of Thermolam, and another of 520. I get a little crazy sometimes. :-)

520 Deco-Fuse Firm

Exterior of bag: Pellon 520 - Interior of bag: Pellon Shape Flex

I love this interfacing. Love love love it. It is wonderful in so many ways. If you are looking to make a very stiff bag, then this is the interfacing for you. Even though it is very stiff, it is about as thick as a piece of construction paper, which makes it reasonably easy to sew. Another good thing about this interfacing is that once it is fused, it never has that 'fused' look. So your fabric will look nice and smooth. It also holds a finger press, so I usually never have to iron any seams, I just use my fingers.

As with any stiff interfacing, it can be tricky to maneuver your bag through your sewing machine. I say sew slowly, and come up with creative ways to get the stitching done. For instance, if you have to sew half a line of stitching, stop, feed the bag in from the opposite side to continue stitching, do that. Honestly, no one is going to see the wrong side of your bag, so it doesn't have to be the prettiest stitching in the world (in my opinion).

520 Deco-Fuse is a great way to get a store-bought look to your bags.


Peltex 70 Sew-in

Exterior of wallet: Peltex sew-in and Pellon Thermolam - Interior: Pellon Shape Flex

This interfacing is a little bit thicker than the 520 Deco-Fuse, and it is stiff as well. It comes on a bolt with a yellow label. Because it is a sew-in interfacing, it will not fuse to your fabric. You can either baste the interfacing to your fabric using a small seam allowance, OR (and this is my favorite method)...you can cut a piece of Shape Flex that is the same size as your pattern piece. Then cut a piece of Peltex sew-in from your pattern piece, but trim it 1/2" smaller all the way around. Center the Peltex sew-in on the wrong side of your fabric, then place the fusible side of your Shape Flex on top. When you fuse the Shape Flex, it will seal the Peltex sew-in along the 1/2" edges against your fabric. Having a smaller piece of Peltex sew-in will also help to reduce the bulk in your seam allowance.

Another great reason to have some Peltex #70 around is for bag handle inserts. Some sewing patterns for bags call for you to create sort of a double-bias piece for each handle, meaning that your raw edges would not be exposed. I cut a strip of 1-1/2" wide Peltex #70 for each of the handles in the bag below, and slide them into each handle piece before topstitching along each long edge. It makes the handles very stable. I've also used fusible fleece and Thermolam as handle inserts before. I suppose it just depends on what look you're going for, but any will work.


I definitely favor the 520 Deco-Fuse, but Peltex Sew-in is a great substitution for that.




Peltex 71 Single-sided Fusible

Exterior of bag: Peltex #71 - Interior: Pellon Shape Flex

I used to use this interfacing all the time. However, with the release of 520 Deco-Fuse, the Peltex fusible has sort of taken a backseat in my stash. It is great when you want to fuse a small area of a project (such as the flap of a bag or clutch), but I find that sometimes when you are using it on a larger area of a project (for example, the exterior of a bag), it *can* give the fabric a 'fused' (aka crinkly) look.


It is a stiff interfacing like the Peltex Sew-in and the 520 Deco-Fuse. If you need a heavy/stiff interfacing that you'd like to fuse, I'd say go with the 520 Deco-Fuse.




809 Decor Bond

Exterior of bag: (red area) 2 layers of Decor Bond; rest of exterior is Thermolam - Interior: Shape Flex

I began using this interfacing quite a bit, late last year. If there are panels or handles of a bag that you would like to give a stiff appearance to, but not want to look crinkly if you happen to fold or crease them, this is the interfacing for you.

Actually, I use this interfacing in 2 layers. I will first fuse a layer of Shape Flex against the wrong side of my fabric, and then follow up with 2 layers of Decor Bond. However, the Decor Bond I will cut approximately 1/2" small on all sides of the particular pattern piece, to keep bulk out of the seam allowance.

You can also use a layer or two of Decor Bond if you want your bag to stand up by itself, but not be as stiff as Deco Shape or Peltex.

Psssttt! Did you know that if you don't have any interfacing handy, Pellon Wonder Under (a fusible web) will turn any fabric into a fusible interfacing? For example, you can use Pellon Nature's Touch or Warm and Natural batting in place of Pellon Thermolam, or another quilting cotton in place of Pellon Shape Flex. How's that!!


I hope this article has shed a little bit of light on bag interfacing. I know it's something that we don't talk about a lot, but we probably should, because it's one of the things that sewers can find confusing, and I get asked a lot of questions about it!


Many sewing patterns only name interfacing in generic terms: light-midweight interfacing, heavyweight interfacing, etc. That can make it sort of difficult to navigate. To generalize, I would say, in my opinion, that for a light-midweight notation, you can use Shape Flex, fusible fleece, or Thermolam. Heavyweight or stiff interfacing would be either of the Peltex or the Pellon 520 (possibly 2 layers of Decor Bond). Again, others might have different opinions on this.


A no-reply blogger (meaning, I have no way to contact her!) just asked me about washing these...I have washed bags made out of just about every interfacing. You can do it, some just look a bit more wrinkly than others (bring out the iron!). I'm not really a big fan of washing my bags, though, so I wouldn't do it unless you had some sort of emergency (like grape juice).

There are no right or wrong answers to using interfacing. I find that the best way to learn more about it is to use it in all of your projects...tweak your interfacing based on your personal preference: what kind of shape are you interested in, how much stiffness, what kind of body.


Feel free to ask any specific questions about interfacing in the comments! I will answer! If you are working with a certain pattern, feel free to let me know if you're confused on what interfacing to use, and I'll be glad to help you navigate the waters!