I'm with SonnyE on this alum is used to crisp pickles. Also in bread and butter pickles we use to ice down the slices for a period of time then cook them as recipe said and they would be crisp. Don't think there is any after the fact way to make them crisp.
I did ice them down for about 5 prior to processing, but I can't find the recipe that I used. I don't remember using any alum like my grandmother did. Didn't know if that was the reasoning why they didn't firm up. I think I'm stuck with what I got, have to go back to the drawing board on the new crop. Thanks all...
You can use Pickle-Crisp made by Ball, grape leaves also work. The FDA now warns against the use of Alum for pickles. I make Sweet, Bread and butter and Dill (all quick process from Mrs. Wages), the only ones I ever had a problem with were the dills.
If making chips, make them about 1/4" a mandolin helps with speed and consistency. I put mine in a bowl and fill with water and put them in the fridge for a few hours, this helps crisp them up. Also if you can make your brine and let it cool down a fair amount this also helps. Then process for your altitude. Let sit for at least 2 weeks and then put in the fridge for a few hours before opening, you'll have good crispy pickles.
Also if you grow pickling cucumber to make your pickles and have to wait several day between picking to get enough to make a batch, wash, slice and put in water until you have enough. That keeps them better than just letting them in the crisper drawer.