I don't have an easy way to crush these grapes. It sure would be great if I could get them destemmed an crushed! But I don't have that tool at the moment. I'll keep an eye out for sure.
Without crushing, you are doing basically a "whole cluster press" (but you de-stemmed them -- which is not really need, or actually ideal, if using a basket press). Most commercial basket presses are the wrong tool for doing this. They are too narrow and tall. Short, very wide, presses are what is needed in order to break the berries during pressing (or modern tools such as continual pressing). Else, you usually get what you got -- a lot of uncrushed berries. You can crush and press in your press if you do many separate layers of pressing, adding layers as you go, maybe dismantling and fluffing the grapes now and then as well as you progress.
Also, with a basket press, if these are white grapes, leave in some stems. Helps to drain off the juice and may facilitate more berry crushing. If you get grapes getting squeezed out the basket, you may be pressing too hard (pressing harder probably will not crush more berries, but may break seeds which you don't want to do).
Or you can just hand crush the grapes. Or stomp on them as a centuries old method. Personally, I suggest a modern addition of using sanitized plastic boots exclusively used for this purpose and which never touch the ground -- put them on in the stomping bin. Many reasons I suggest this, such as avoids getting stung by any wasps hidden in the clusters, as these guys mentioned:
But if you rather do it bare footed.... at least try to get a friend to help.
I think they're certainly some sort of champagne grape, or white grape. They definitely aren't dark colored
I think a photo of your grapes may help, because a "champagne grape" is actually a
common name of corinth grapes. And grapes that make champagne are different, and actually are both red grapes, such as Pinot Noir and Pinot Meunier, or white like Chardonnay.
and this year I let them ripen to almost raisins.
That may explain also why you got less juice.
woah, If I let the ferment go 3-12 days, it will change the flavor a bunch? This time I've got two buckets going, about 7 gallons each primary fermenters. I was thinking of letting the primary fermentation go a whole 14 days: but that might screw it up? Err, make it so I'm "sucking tannin & herbs?"
If these are white grapes, you do not ferment on the skin (and almost certainly not the stems). Unless you want to make an amber wine (which if done wrong, can smell bad).
And without skins (and stems), there is no worry about getting extra tannin or herbaceous issues. However, if left to sit on the lees post fermentation too long, that can cause other problems.
And "time" is not really relevant. Time to complete a fermentation can vary a lot. Fermentation progress should be checked with a hydrometer (relatively cheap to buy).