Do Grading Coin Companies Clean Coins ?

Nice! I love the washing machine cleaning reference. So basically to my understanding, cleaning when detected reduces the value tremendously. Some collectors or buyers won't even look at your item. Some may consider buying it to fill in spots in their collections or because the coin is a key date. You could expect a 50% or more reduction easily.

Now, being labeled cleaned. Because these coins are made of such malleable materials, even the softest brush can leave a mark on a coin and using liquids that help remove dirt can also remove luster or shine to the coin and also cause what called pitting. Which makes your coins surface look like the moon(full of craters). All of these are easily detected by seasoned collectors.

I have seen grading companies clean coins before, but this was for extraordinary treasure finds where they stand to be associated with such a find and probably stand to make a ton of revenue. Other then those situations, I don't think they provide that service.

I don't think they "clean" coins but they do/will conserve them for you at an extra cost.
John1

I agree. But the cost of conservation and NGC encapsulation is often high enough that only valuable coins ($1000+) will be worth the price to do so.

Using pure acetone to soak off some contaminants is about the only type of "cleaning" that is suggested.

ICG will for free if it needs it, they all have conservation services.

Otherwise no they won't if you don't pay them

Amateurs CLEAN coins. Experts CONSERVE them!

So the simple answer is yes, there are things that can be done to a coin safely to improve its appearance-let us call this cleaning. Many threads in this forum have discussed this. I am also sure that the grading companies have some special techniques.

The big however is that there are many MORE things that can be done that will harm a coin, so you really need to know before you start if your choice is harmful or harmless.