No knife needed. Cut a cake like a pro with dental floss


Use dental floss to slice your cake.

James Martin/CNET

Delicate Piping: Ruined. Glazing: a long smear. Crumbs piled on top of what was once a perfectly frosted cake. These are all signs that you used the wrong tool to cut your cake, even if that tool was a knife. No matter how sharp it is, every time I use a knife to cut a cake, I often have a drop of frosting left over that I end up scraping off someone’s plate to “clean” the blade for the next slice. But what other option do I have? Surprisingly, a small everyday tool does the trick: dental floss.

A spool of dental floss fits easily in a kitchen or office drawer, or in a work bag, and it’s always on hand. I recently tested five types of dental floss to cut three types of cake. The result: some of the cleanest slices that any professional baker would be proud of. I am not joking. This method works fantastically well, and it’s surprisingly easy to do.

The only downside: flossing might not be the most elegant way to cut cake slices, and you might get icing on your fingers. But the results are worth it. Here’s how to floss your cake, what kind of floss works best, and some pitfalls you should absolutely avoid. For another cool kitchen-related tip, here’s how to make distilled water for free.

Why use dental floss to cut a cake?

There can be a number of reasons why you use dental floss instead of a knife to cut the cake. Maybe you’re at the office or at a birthday party in the park and the only cutting utensil available is a 6-inch compostable knife. Maybe you’ve had enough of the buttercream buildup and want to try something new. A colleague saved the day at a party when a giant cube cake appeared in a bar that had no utensils for guests. Luckily, the container of dental floss she had on hand did the trick.

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Here’s why it works: A strand of dental floss is typically thinner than the blade of an average kitchen knife and is designed to slip easily into tight spaces (i.e. between your teeth). If you’ve ever flossed too aggressively, sore gums are the only proof you need that the “edge” of flossing may be sharp.

Add them together and you have a pretty ideal instrument that can give you clean, crisp slices after cutting. When cutting a cake, I could barely see where the floss was going through the icing because the cuts were so clean.

In my experience, using dental floss to cut the cake also helped preserve the delicate decorations better. For example, the carrot cake I used for this test had a pattern of piped carrots on top of the cake. Cutting it with dental floss kept this design intact. In my experience, using a butcher knife to cut decorations often ruins the look, leaving a smudged pattern – but that depends on the sharpness, width and length of the knife blade.

And this problem of icing accumulated on the edge of the knife? Almost gone – except for the buildup on your fingers.

cake cut with dental floss

Pro tip: Slide the floss through the bottom of the cake for a cleaner cut.

Katie Teague/CBS

How to cut any cake with dental floss

First, make sure your cake is on a flat surface so you have room to pull the yarn all the way to the bottom of the cake. You can put it on a cake stand to give you more room when cutting. Next, wrap a length of yarn larger than the widest part of the cake. I left several inches at each end to comfortably wrap the floss around my fingers. When you wrap the dental floss around your fingers, don’t make it too tight: you’re trying to cut a cake, not your fingers.

If you’re trying to make each slice the same size, you can use dental floss to lightly mark the guidelines before cutting the cake.

Ready? Here’s what to do.

Square or rectangular cake: If the cake is shaped like a square or rectangle, it may be easier to cut it as these cakes are usually shorter than round cakes. Using your dental floss, make your cuts on the cake lengthwise, pressing firmly into the cake to cut all the way through. Now make your cuts widthwise, cutting all the way to the bottom of the cake.

Round cake: If your cake is shaped like a circle, it may be a layer cake, so you may need to apply a little more pressure to make it all the way to the bottom of the cake. Using your dental floss, firmly cut the center of the cake to create two halves. You may need to move the floss in a sawing motion to cut it completely.

Next, make a cut perpendicular to the one you just made – you should now have four triangles. Continue making cuts, moving around the cake, until you have the number of slices you need. Note that the thinner you want your slices to be, the harder it will be to cut as the slices start to fall apart.

cake cut with dental floss

Dental floss is best for cutting thinner slices of cake.

Katie Teague/CBS

Can you also use dental floss to serve cake slices?

To see if it was possible, I tried to pick up a slice of cake with dental floss. It was tricky and a little worked, but the wire slowly cut through the spongy texture as I tried to pull the slice out. Instead, I suggest using a serving fork or knife to deliver the slices to a plate.

My pro tip for cutting a cake with dental floss

When making cuts, once you’ve cut down, don’t pull the thread up. First, it will make your yarn more messy, which means you’ll have to get a new strand every time you make a cut. But more importantly, pulling the slice up brings crumbs to the top of your cake and also lifts some frosting, so you don’t get the clean, tidy look you’re looking for.

Instead, once you’ve cut all the way to the bottom of the cake, let go of one end and remove the floss. Most of the icing and crumbs on the floss will be brushed away as you remove the floss, and you’ll end up with a clean strand that you can reuse to cut the next slice.

Here’s Where Flossing Didn’t Do Its Job

When cutting the larger cakes, I noticed that the floss sometimes did not easily cut all the way to the bottom, perhaps due to the increased resistance. If this happens to you, I suggest cutting the cake in half first, then working with each half so there’s less cake—and resistance—to cut. It may also be helpful to put the cake on a stand to help you slice it completely.

Another note: if you are baking a cake at home, this method will only work if you first remove the cake from the baking dish or cake pan.

Beautiful even slices of carrot cake

Nice even slices of cake.

Katie Teague/CBS

What type of yarn worked best

For my tests, I used waxed dental floss from Kroger, two types of Oral-B Glide (one mint flavored, the other unflavored), and two styles from CVS store brand: waxed dental tape thicker and regular unwaxed dental floss. I tried the types of floss on three cakes: a layered carrot cake containing shredded carrot pieces, a taller, lighter textured sheet cake, and a shorter, denser sheet cake (almost like brownies).

All the wire worked well and made clean cuts, even with the carrot pieces from the more textured sample cake. Original Glide Floss slices cakes a little easier than Kroger Waxed Floss. I think it’s because the Glide floss was softer to the touch and actually to glide through the cake.

Although I was worried it would snag, the unwaxed yarn worked surprisingly well and made clean slices.

The only one that smudges a bit during a cut is the dental tape – which looks more like a ribbon than a thread of nylon thread. It made a clean slice, though, and I’d use it in a pinch.

Flavored or unflavored dental floss: Will it change the taste of your cake?

I was concerned about whether using flavored floss would also transfer flavor to the cake slices, but we cut pieces of a chocolate cake using mint flavored floss and none of the four taste testers could not detect a mint flavor. To be safe, I’ll stick to plain, unflavored floss if you can, and avoid cinnamon, coconut, or bubblegum flavors.

So the next time you cut a cake, grab some dental floss or something similar, like fishing line, sewing string, or thin thread.


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