scissors won't cut strings

[Lenny Smith]

I have several pairs of scissors. They cut paper alright but when trying to cut cotton strings of less than 1/32" thick, they just slip. What gives?

[rbowman]

How tight are the blades? Are they bowed? Dull?

Better scissors have a hinge screw you can tighten. The cheap ones have a rivet that you can tighten with a hammer although that's obviously trickier.

If you hold them up to light and look at where the blades meet you should see a very tiny gap, if any. If there's a bow between the tips and the hinge.

If they're old, dull, and abused and you plan on cutting a lot of string, maybe spring for a new pair of Fiskars? There are a lot of styles, most under 10 USD.

[invalid unparseable]

Lenny Smith wrote on 1/8/2023 8:04 PM:

Your question is a known problem for people in the garment industry.

The reason a pair of scissors that appears sharp cannot cut a thin cotton thread is because the cotton thread is slipping away while the scissors is trying to cut it. The reason the cotton thread is slipping away is because there is nothing on the blade to catch the thread and hold it in place .

In the old days scissors were made of high carbon steel. High carbon steel has a lot of carbon particles embedded in the steel. When the blade is sharpened to a really thin edge, some of the embedded carbon would naturally flake off and create micro serrations along the thin edge. You have to use microscope to observe the micro serration on the thin edge of the blade. The micro serrations will help to start a cut because it will catch the object you want to cut. That's how you get paper cuts from a piece of white bond paper because there are micro serrations on the paper's edge which catch your skin and initiate the cut.

Modern scissors and knives are made of stainless steel which don't have high carbon content. There are stainless steel scissors that have micro serrations artificially created to simulate the effect of high carbon steel blades.

If you zoom into the photo of this pair of serrated-blade scissors, you can see that there are grain texture in the steel which runs perpendicular to the length of the blade. That's is how the micro serrations are created on the blade when they hone and sharpen the blade on the side that doesn't have the grain texture.

I notice that many cheap scissors sold in Walmart and dollar stores also have similar grain texture on the blade. I guess those will cut fine cotton thread too.

[dyno dan]

True. But the two pairs I have both have screw head slots so narrow that only a very tiny screwdriver blade will enter. That blade is not wide enough to allow enough force to turn the screw.

-dan z- __

[Peter]

Fiskars 8" all purpose scissors have a Phillips head screw at the hinge that can be adjusted if needed with a #1 Phillips head screwdriver. I use it for everything from delicate cutting (sewing thread, paper) to tough items (cutting through the plastic "bubble" on items packaged that way. I've had these scissors for many years. Never needed to adjust the hinge screw. Washable. Very reasonable in price. The packaging included an oval orange plastic scissor blade sharpening tool I've never needed to use. I don't know if the sharpener is still included with the scissors but you won't need it!

[micky]

If you twist your hand the right way, you can make the blades of the oldest, sloppiest pair of scissors press more tightly against each other. This should help a lot. But there is no substitute for being sharp. Or switching to a knife for some things like strings.

I think once or twice I've hammmeed on the rivet holding the two halves of one pair. It helped. I've never tightened a pivot screw, maybe never had one with a slot.

BTW, I'm told that paper will dull a pair of scissors but many other things won't or won't nearly as fast. So in theory I should reserve one pair for paper.

In practice, when I used scissors to trim my beard, I buy cheap scissors with orange handles (later they came with other colors) and they work for 5 or 6 years before they seem to be dull. Then I buy another pair and demote all previous pairs. The recent beard pair goes into the desk drawer, the ones in the desk go into the kitchen drawer, the ones in the kitchen go into the car trunk, the ones in the car trunk go to to the basement workbench. Well in theory. Somertimes I go straight to whatever spot is missing a pair of scissor.

I bought an electric beard trimmer that works well. Good timing because I have scissors all over the house and I don't want to buy more.

These are a few of my favorite strings.

[micky]

Very intersting.

Was your father or grandfather a tailor? Or some other job in the garment district?

[invalid unparseable]

Yes. In the old days all the scissors and thread snippers were made out of high carbon steel. They always tell people not to use their scissors or snipper to cut paper.

Paper fiber is a lot harder than the fiber in cotton thread. If you cut paper, the micro serration (which are like microscopic burrs) on the cutting edge would be bent by the paper fiber, and the scissors won't cut cotton thread until sharpened again. Modern way of creating the micro serration on the cutting edge by embedding grain texture on the steel can handle paper fiber without ruining the micro serration because the micro serrations are not as fine as those formed naturally in high carbon steel.