HeatherArtLife

I am throwing with a "imperceptible grog" white Spanish clay. @JohnnyKYes, water and clay dried there after throwing but in a humid environment for a few days, so corroded. I´d never seen this before and sort of freaked. I will be taking MUCH better care in the future. I throw directly on the wheel but will transition to plaster bats soon... she´s my baby and I just want her sparkle back! Ha ha. 
Thanks EVERyONE. Adore this community. 
xoxo H

222 page thesis
TRANSFORMATION OF SIX LEAVES GLAZE TO CONTEMPORARY CERAMIC BASES ON THE TAOISM CHARACTERISTICS
https://tinyurl.com/4a48pyky
In the research process, 768 glaze recipes have been tried. A total of more than 600 kilns have been fired, and more than 20,000 pieces of products have been fired. In the early stages there were a high probability of failures. However,
the rate of finished products finally increased from 2% to 80%

I am throwing with a "imperceptible grog" white Spanish clay. @JohnnyKYes, water and clay dried there after throwing but in a humid environment for a few days, so corroded. I´d never seen this before and sort of freaked. I will be taking MUCH better care in the future. I throw directly on the wheel but will transition to plaster bats soon... she´s my baby and I just want her sparkle back! Ha ha. 
Thanks EVERyONE. Adore this community. 
xoxo H

I can't see that being any problem.  If you throw on batts you are not on the wheel head.  If you throw on the wheel head there is not enough damage to matter.  I have been throwing on a wheel head in much worse shape than that and have had no problem.  Lin

The wheel head depicted, looks like scoring, wear, and tool marks, and  - but not enough surface worn away where it's easily perceptible (where it looks unflat*).
Excepting that one deep scratch, it doesn't look bad at all, lots of life left. Maybe wipe if off and let it dry when you're not using it.
The only time I'd take any abrasive to the wheel head (or tool, like a file or scraper) would be to remove ridges or somewhat that sticks up. What's done is done; I'm not seeing any reason to remove material to clean up the markings/pits/scratches/divots.
If working directly on the wheel head, there's going to be wear.
If leaving a clay pad (wet dirt), or somewhat else wet on there for days, likely there's going to be some pitting or deposition.
*some of the older wheels in the local JC lab have significant wheel head wear. They don't run out (wobble up and down or shift side to side) at all, hence, they work just fine. When the material is so worn away that the head is weakened, well, that should take a while, and by then...

I have really hard water. I have to descale my kettle probably twice a month, but I’ve never known it to affect my wheelhead. To get lime scale you have to evaporate a few gallons of water, not the amount you throw with.
I used to get similar discolouration when I was using a cone 10 porcelaneous stoneware, but if you clean your wheelhead it doesn’t really form. I haven’t had any since I’ve switched to red clay. If it got bad, I’d occasionally take some 220 grit black sandpaper to it, but mostly it wasn’t an issue. 

Al U Minium  and  Al K Li  have been in a feud since the beginning. 
The issue here is corrosion of the metal from the wet clay body and the slips that develop during throwing sessions;, not just depositing lime from water.  
The alkali mostly comes from porcelain type clay bodies, but not necessarily always; depends on clay body recipes.  Cast iron wheels does not have that problem (iron wheels will just become iron rusts).  There are a few aluminum alloys that will not corrode in certain alkali environments, but the cost is very high.   
hard water will crust on the surface as lime and lime carbonate, but is not by its self a significant corrosion problem. 
LT
 

Oh, thanks @marc and @Hyn Patty! Appreciate it!!