Does anybody know of a good product or home made solution to remove dried salt from porthole glass?

I have tried white vinegar and a lot of elbow grease. But, that dried salt will just not go away.

We just rinse with fresh water. Salt is 100% water soluble. Even after days in the sun and wind, the salt just washes off our Eisenglass dodger windows, and they are a lot more prone to scratching than porthole material.

Mild acids like the acetic acid in vinegar should be good for removing residual calcium carbonate, but there are more aggressive products you can buy in a hardware store for removing lime scale that may work better. Before you try one of them I would try to increase the contact time by soaking a cloth in vinegar and securing it against the window for a while. Increasing the temperature will also increase the rate of reaction, moderate warming might help the process along.

CLR diluted in hot water.

Are you certain that you are dealing with dried salt and not abrasive scratches for example?

If it is salt, as the others said, that's water soluble and letting it get damp (cover with damp paper towels & wait) would let it come off easily.

If it is NOT salt, and the portlights really are glass, one alternative is to take a fresh single-edged razor blade and carefully hold it at a low angle, and scrape. Unless you dig a pointy corner of the blade into the glass, this works on windshields, glass stove tops, portlights, windows, no problem. Some folks will take a stone or fine sandpaper and just round off the corners of the blade to make sure it can't nick.

Home-made glass cleaner often is salt and lemon juice and water, so perhaps a little lemon juice would also help.

Thank hard: If it is not salt, what else could it be?

Thank you for the responses.

I use vinegar and calcium lime rust remover.