Why does the supplied type C, charging cable, feel sticky, powdery and leaves white residue on my hands?

Given power cables sometimes have a history of need to be cleaned on occasion,

seems to me that you could try one of the methods (re: non-corrosive damp wipe

only on cable insulation) to include product such as armor-all that leaves protective

film on surface, after cleaning. This may be a final finish to a cleaning effort.

Even outdoor extension cords get messy stuff on them; just avoid industrial cures

to clear a surface condition. One of the organic orange cleaners may do. I've cleaned

many different products, including vintage film camera gear and computers, so do

have several ideas that could be workable; and not void warranty or melt the cable.

Or wear an apron whilst using the MacBook, to avoid the oxidized chalk-effect! 😜🌩🙃

Again, there is no such thing as a 2018 MacBook. You may have purchased it in 2018, or even earlier this year (Apple no longer sells them), but it is still a 2017 model. Regardless, my concern is that you may not have purchased a genuine Apple product and why I provided you with what the box that it would come in look like.

Inside the sealed box you should have also found a power adapter and a single USB-C cable. That cable should not show any signs of corrosion or damage. Regardless, unlike you, I have never come across anyone, including myself, with cables that Apple provided with their new devices that had these issues that you describe.

Great, then any accessories would be covered with that AppleCare+ plan as well. I'm not sure why you are getting cables that appear to be defective. Not sure what else I can help you with on this matter. Be sure to give Apple an opportunity to make this right if you are not satisfied. Even raising it up the Apple management chain, if needed. Good luck!

Maybe because Apple does not sell a 2018 MacBook 12" model. They did; however, sell a 2017 model with Model Identifier: MacBook10,1 and Model Number: A1534. It would come in a box with a side image of the MacBook on the cover, an Apple logo on both end sides, and the word "MacBook" on the other sides. It would also have a number of identifying labels on the bottom which would include the notebook's model and serial number. Is this what you got?

Once again, there is no such thing as a 2018 model. You purchased a 2017 model in 2018:

Click on the Apple menu's "About This Mac," and read what it says.

We have encountered this white powder when opening brand new Apple cables recently. I'm guessing it is just not being cleaned properly during the manufacturing process.