Red or black ?

For this trick, you can use any deck without joker, which the spectator can shuffle.

Start by asking the spectator to cut the deck in half, and to choose which part to keep. If they want, they can shuffle it again.

Next, they can take a card, without looking at it ! Ask them if they think it's red or black. Turn the card over, if it's black, put it on your left, if it's red, put it on your right.

Repeat the same operation but pick a card of the other color, to create 2 piles. Next, repeat the same thing with 3 red cards, but do not show them face-up ! Put the cards wherever the spectator wants. You can finally do it with 4 red cards, and then the red cards left.

You should now have only black cards. Take one and deal it face-down. Ask to your spectator the color, to "see if they are lucky". Turn it over, and put it in the black pile face-down. Remeber what card it is, it will be your key-card.

You can now give the whole deck to the spectator, which they can shuffle and place wherever they want, without looking at it face-up !

Finally, take the "black" pile, and deal the top card face-up, until you see your key-card.

Next, take the "red" pile, put it on the "black" one fast, flip the whole thing and spread it from the left to the right. The spectator should have the impression that all cards were correctly sorted.