I like hot dogs, bite into a good wiener and it snaps when you chow down on it, a mushy hot dog - YUCK. I like my pickles the same way, that crispy crunchy pickle texture is the first indication that a batch of pickles has been successful.
Unfortunately for many novices to the realm of pickling a few simple mistakes will lead to less than desirable imperfect pickles, the taste of a mushy pickle is wholly inferior.
There are several steps that should be taken to ensure your pickles are crisp and crunchy.
1. Use pickling cucumbers, not salad or slicing cucumbers whenever possible. Standard salad pickles are workable but not ideal for pickling. Salad pickles tend to be thicker, larger and contain more seeds. Pickling cucumbers are generally not as thick, in fact most of the best pickling cukes contain the word "pickling" in their names, such as Boston Pickling Cucumber, Bush Pickle and Northern Pickling Cucumber. See - Cucumber Varieties
2. Use only fresh cucumbers. Cucumbers that have been stored for any length of time become less desirable. They should also be as close to the peak of ripeness as possible without being over ripe.
A slightly overripe cucumber that betrays any signs of yellowing or swelling is still good for a salad or snack, but avoid using it for pickling. Fairly thin and dark green cukes are best although this varies somewhat among various cultivars.
3. Cut off the Blossom End of any cucumber you decide to pickle, just before you pickle - not a few hours before hand, but just before putting it in the brine. Just a small nip is all that is necessary. The very tip of the blossom end contains a plant enzyme that alters the chemical balance and can at times cause your cukes to soften.
4. Over-Processing Even if you followed all the suggestions above, if you over process your pickles you could still end up with soggy pickles. If using a hot water bath, before you pack your jars in only when it is near the boiling point - placing them in early and then boiling the water causes them to be heated for too long and hence they probably will not be crispy.
5. Ice Water Soak. It's very simple - just pack the cucumbers or other vegetable in ice for roughly 4 hours before pickling. You can also use salt with the ice although it is wasteful in my opinion.
6. Added ingredients that help create a crispy pickle include....
A. Alum is an old timers trick to helping create a firm crispy pickle. Unfortunatley those young whipper snappers at the FDA reccomend against it. Alum reacts with natural pectin to firm the texture but it is also know to detract from the taste and give some pickles a slight bitter taste. Alum is found in Aluminum metal as well and there is some indication that it may have adverse long term health effects.
B. Pickling Lime is calcium hydroxide, it chemically reacts with natural pectin in fruits and vegetables to form calcium pectate, giving the pickles a firmer texture. The drawbacks to pickling lime is that it makes it less likely that the vinegar alone will be sufficient to ensure a safe pH for you finished product. Don't use pickling Lime unless a reliable recipe actually calls for it. It should not be added to the pickling brine.
The best way to use pickling lime is to soak fresh cucumbers or suitable vegetables in cold water with 1.5 to 2 Tablespoons of lime per gallon of water. THOROUGHLY Rinse off the lime residue on the cucumbers before using them.
C. Grape Leaves. As per old wives and picklers from yesteryear if you place grape leaves in the brine while fermenting or in the pot when processing, your pickle wont get soft. Like many "Old Wives" tales, there may be some truth to this. Grape leaves it has been discovered contain a natural inhibitor that reduces the effects of enzymes found in cucumber blossom ends. If you cut off the blossom end as suggested in step 3 above the grape leaves serve no function.
D. Calcium Chloride which is marketed under the trade name "Pickle Crisp" is a firming agent used in Pickling. As of yet, there are no reported adverse issues or effects from using it in Pickling. But who knows, we used to think drinking from the hose was safe. I've tried it and was happy with results - use as per manufacturers instructions.