Ahh. I haven't looked at those, but I would assume:
- no abrasives
- just as caustic (basic) as powder dishwasher detergent.
So if abrasion is the only problem, dishwasher liquid is safe.
I wouldn't expect caustic to corrode stainless steel tools at all, but maybe some shears use high-quality carbon steel. See below.
If you do worry a lot about corrosion, maybe you should worry about leaving carbon steel WET in the dishwasher for 40-50 minutes, regardless of chemicals. I wouldn't let carbon steel that I cared about (a knife) sit wet in hot distilled water for the length of time a dishwasher runs.
Plain water rusts carbon steel too much for my taste!
Hand-washing is faster than a dishwasher. Or give it 3-5 minutes in the soapy cycle, then pull it out, rinse, dry and oil. Dishwasher interruptus.
That said, if it was not a knife or a classy pair of shears with carbon steel blades, I would not worry a bit. Some spades and rakes, I leave wet and muddy for days! So it's a personal value decision.
Are there any grounds for concern about accelerated caustic corrosion with carbon steel? I'm not positive. Even if it DOES take any shine off a carbon-steel trowel, it might replace the shine with a patina like "blueing" and resist further rust.
But if you're trying to keep carbon steel tools shiny, get someone else to try the experiment first!
Joanna, what do you find? Do you know if your dishwasher removes any of the shine from plain old carbon steel tools, the kind that rust if mistreated? The picture in the Idea shows many shears, several with blades that look like carbon steel, perhaps with very dark blueing or some kind of coating I would not expect on stainless.
- Don't run it through the electrically-dried cycle if you worry about corrosion.
- Definitely rinse carefully afterwards and then oil it promptly if it's carbon steel.
- If you wouldn't let your garden hose spray cold, clean water on it for 50 minutes, don't put it in the dishwasher for 50 minutes in very hot, slightly caustic water.
- - Nerd Addendum - - - -
Online advice about caustic and carbon steel was a little varied, but the impression I took away was that only STRESS-corrosion cracking is any concern, until you get to 50% NaOH and above somewhere around 150 F or 50 C. And maybe, even above those limits, it's still only SCC that they were referring to. And SCC is about micro-cracks becoming bigger and weaker over time and stress ... stress like "in a bridge", or high-pressure pipes, or an automobile suspension.
So partly, I would guess that SCC ought NOT to be a big concern for hand tools.
On the other hand, hardened knife steel or shear edges could retain SOME stress from heat-treating (even after annealing). And it doesn't take much corrosion to dull a really really sharp edge.
>> 50% NaOH and above somewhere around 150 F or 50 C.
I think dishwashers approach 150F - and exceed it during the dry cycle.
Offhand, I would expect dishwasher powder or liquid to be much less strong than than 10% or even 5% sodium hydroxide. So there should be a safety factor of 5 or 10 on the concentration of the caustic detergent. After all, you can dish-wash wood many times before it softens, and it doesn't strip the hair and skin off your hands. So how many annual washes would it take to affect carbon steel at all, even if it does turn out to be slightly vulnerable?
Dull a shine? Dull an edge? (on carbon steel, not stainless)
I can't be sure, but I would GUESS not very much.
P.S. Acid, like vinegar, etches and corrodes most metals MUCH faster than caustic does.
So if you have very acid water, maybe the dishwasher is SAFER for carbon steel than tapwater would be!