My wine won't clear
First of all, if your wine is cloudy, don’t try to bottle it, because it won’t clear in the bottle. In fact, you’d have wasted your time, since any extra treatment you do to clear the wine would require you to dump out all the bottles, process the wine, and re-bottle.
Secondly, don’t filter the wine to clear it. Filtering is only good for clearing wines that are already almost completely clear. Fining agents still in suspension would quickly block your filter pads, and those that make it through would simply show up as sediment later on. So this would be another waste of time and money.
Your first step, if your wine hasn’t cleared, should be going back to the instructions and carefully reviewing them to be sure you followed the fining procedures exactly. Winexpert kits want you to add bentonite on the first day, while others want it on the 20th. Some kits must be racked prior to fining, and some must not be racked or the finings won’t work at all. But you’ll notice that the instructions regarding fining all contain the same phrase:
“Stir the wine vigorously”
Which actually means, really, really, really vigorously. In order for the finings to have the proper effect on the wine, it needs to be free of carbon dioxide. If it’s not, the fining particles will attach to the bubbles of CO2 and float back into suspension, over and over again, so that nothing settles out. So stir the wine until it stops fizzing. You may help this process if you warm the wine to the upper end of the specified temperature range; remember that CO2 is soluble in a liquid solution in inverse proportion to the temperature. When the wine is warm, it will be much easier to de-gas.
This leads to the next step: check the specific gravity. If the wine had not finished fermenting before you added the finings, you’ll have no option but to have to wait until it does. Nothing you do will influence the clarity until the yeast is finished fermenting all available sugars in the juice.
If all of the above suggestions are in order, double-check the instructions regarding temperature. While some fining agents work very well under cool temperatures (bentonite, kieselsol, etc), others (chitosan, isinglass) stop working at all below specified temperatures. Many grape winemaking textbooks advise lowering temperature to help the finings work but make sure this agrees with your instructions before you do cool the must down.
So, if your gravity is correct, and you’ve stirred the wine sufficiently, and you’ve got it at the right temperature, the best course of intervention is simply to wait an extra week and see if it clears up on its own. The principle of least intervention applies to all fining activities: try to get the most effect with the least amount of added finings and effort.
However, if weeks of patience don’t seem to make a difference, you can probably add an extra dose of finings. Use the same fining agent used in the kit, at a rate of 50% of the original dose. If that turns out not to be an option, the fining agent Sparkalloid is an excellent choice. It’s a little complicated to use, but the combination of carageenan proteins and diatomaceous earth makes it a very effective clean-up fining. Use sparingly and follow the package directions precisely.
If you do wind up stirring extra fining agents into the kit, be sure to increase the sulphite levels to match the extra processing and handling. As a rule of thumb, you can add an extra 1.5 grams per kit (one-quarter teaspoon) to offset any oxidation from the handling.
Excerpt from Winexpert