Autoclave will deform the needle even more. The edge of the tip is made from softer steel so that it is sharper while at the same time more deformable.
Assumably also for manufacturing and safety reasons. You don’t want the tip of a needle to shatter inside you, softer steel won’t do that. And it’s a little bit easier to manufacture with softer steel as well.
Needles were autoclaved and re-used once upon a time, so it should be possible. But disposable needles are probably made of softer material than reusable ones.
Those were made up harder steel which can’t be sharpened to the degree softer steel can be. Harder steel shatters if sharpened since harder it is brittle it becomes.
So reusable needle are blunt, so injections are painful. And as mentioned by @Natanox@discuss.tchncs.de they used to shatter inside the body after a few cycles of autoclaving.
It’s a little misleading in that the last photo is zoomed in a lot more than the previous ones. This one has that without the extra zoom in.
Comparing the pictures it looks like the exact same set of photos except like you said, more zoomed in.
Could they be cleaned with isopropyl alcohol or an autoclave?
It’s less about the dirt than the tip deforming.
When the needle is less pointy, it’ll hurt more.
Not only that but look how it forms a freaking fishing hook on the end like a barb. Yikes!!!
Autoclave will deform the needle even more. The edge of the tip is made from softer steel so that it is sharper while at the same time more deformable.
Assumably also for manufacturing and safety reasons. You don’t want the tip of a needle to shatter inside you, softer steel won’t do that. And it’s a little bit easier to manufacture with softer steel as well.
Needles were autoclaved and re-used once upon a time, so it should be possible. But disposable needles are probably made of softer material than reusable ones.
Those were made up harder steel which can’t be sharpened to the degree softer steel can be. Harder steel shatters if sharpened since harder it is brittle it becomes.
So reusable needle are blunt, so injections are painful. And as mentioned by @Natanox@discuss.tchncs.de they used to shatter inside the body after a few cycles of autoclaving.