Good pressing takes time and practice, but it can make any quilt shine. That’s why tailor’s clappers are one of our favorite tools here at the Suzy Quilts HQ. We wanted to learn more about this beloved quilting tool, so this post is all about the science of getting flat seams using a tailor’s clapper!
Having flat seams is a goal for many quilters. Flat seams can make your accuracy, piecing, and quilting easier. You can get crisp, flat seams by adding a tailor’s clapper to your pressing, but some quilters are hesitant to take the plunge and give them a try. Keep reading to learn not just how tailor’s clappers work, but also the science behind why they work!
(Note: I am no longer 38 weeks pregnant - we have a wonderful 10 month old now!)
Today we have a Q&A with my husband Mitch! He’s a scientist by day and has a PhD in Materials Science, which is the study of how different types of materials function. He’s also a talented woodworker (see the picture below of the dining room table and wall art he made for our house!), and as a supportive and curious partner, he has learned a thing or two about quilts.
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How do you use a tailor’s clapper?
A tailor’s clapper is a wooden tool that is placed on sewn seams to help keep them flat after pressing. Here’s a video that shows how to get flat seams using a tailor’s clapper.
Why do quilters get such flat seams using a tailor's clapper?
Heat and steam make fabric fibers flexible, and when they dry and cool to room temperature they stay in the shape they were when hot. That’s why pressing works in the first place! But when you’re just pressing, you remove the pressure of your iron while the fabric is still hot, so the fibers can relax out of shape before they cool and stiffen.
So a tailor’s clapper keeps the heat and steam trapped for an extended period of time, which gives the fibers more time to get into the desired shape - meaning perfectly flat - and then holds them in that exact shape while they cool.
Here are some pictures Laura took of an experiment she did. You can see the difference over time between a seam that was pressed with a tailor’s clapper and one that was not. For both blocks, she used steam while pressing.
Should you always use steam to get flat seams using a tailor’s clapper, or will just heat work too?
Using steam, either by filling your iron with water or spraying water from a bottle onto your fabric before pressing, helps the fibers relax even better into your desired shape. So it’s more effective to use steam, but you will still get some of the effect of the tailor’s clapper from just heat alone. By using only heat, you’re not unlocking the full potential of the tailor’s clapper, and your seams may not be as perfectly flat as they would be if you did use steam.
Are special kinds of wood used to make tailor’s clappers?
A dense wood will hold the heat and steam in the fabric longer, which gives the fibers more time to adjust to being completely flat. The conventional wisdom is that this means using a hardwood like maple or oak. However, the terms “hardwood” and “softwood” actually come from the type of tree, not the actual hardness of the wood. Many hardwoods are actually very soft and light. Denser woods are usually better, but any kind of wood can give a similar effect in flattening seams.
Does the weight of a tailor’s clapper matter?
A heavier tailor’s clapper is better because it will help keep the fabric pressed perfectly flat, but any pressure is better than none. It only has to be heavy enough to hold the fabric flat, but applying any additional pressure beyond that will not make your seams any flatter, so don't worry about applying any extra pressure or pushing your clapper down while your fabric cools.
Can I use a different material as a tailor’s clapper, like ceramic or plastic?
The moisture from your steam has to have somewhere to go so that the fabric can dry. Wood has pores through which water can move and escape, so non-porous materials like ceramic or plastic won’t work in the same way because your fabric will just stay wet underneath.
Why don’t tailor’s clappers have a finish?
A finish on wood is a chemical that closes off the pores in the wood’s surface, which would prevent moisture from being able to pass through it. Since you need the moisture from your steam to be able to escape while your fabric cools and dries, a finish would prevent that from happening.
In your opinion as both a woodworker and a scientist, is a tailor’s clapper a helpful tool for quilting?
Absolutely! The fibers in your piecing don’t want to stay flat after you’ve pressed your seams. Keeping that fold in place to get a seam that lays flat is much easier with a tailor’s clapper - it’s science!
Thank you so much to Mitch for answering some of the most common questions we get here at the SQ HQ about tailor's clappers! If you want to order one of your own, the tailor's clapper in this post is made by the quilt tool woodworking business Modern American Vintage.
Do you use a tailor's clapper? Are you planning to try it out after learning about how it works? Let us know in the comments!