Why won’t my Slushi freeze?

You poured in your drink, picked a preset, and waited. The machine is humming, the mix feels cold, and it is still soup. The good news is that a batch refusing to slush is almost never a broken machine. It is usually the mix itself: the sugar balance, the alcohol level, the starting temperature, or how much liquid is in the vessel. Work through the checks below in order, change one thing at a time, and most batches come around.

Start with the sugar

Sugar does far more than sweeten your drink. It sets the freezing point of the mix, and that is what lets fine, soft crystals form and keep moving instead of locking together into a solid block of ice. Every liquid you pour in needs at least 4 percent sugar, which you can read straight off the nutrition label as 4 grams of sugar per 100 millilitres.

Too little sugar is the most common troublemaker. Diet drinks, no added sugar juices, and drinks sweetened only with artificial sweeteners fall short, and the mix freezes in a hard layer on the drum while the rest never becomes slush. The machine will often tell you: if the temperature lights chase downward one at a time and the unit beeps once a minute, sugar is the problem. Stir in 1 to 2 tablespoons of syrup, juice, sugar, honey, agave, or maple syrup for every 8 ounce serving, then restart the preset.

Too much sugar causes the opposite failure. Very sweet mixes built on cordials, syrups, or sweet liqueurs can sit liquid for hours because all that sugar pushes the freezing point down too far. Dilute the batch with 1/4 cup of water per serving and give it more time.

Check the alcohol

Alcohol freezes at a far lower temperature than water, so a generous pour works directly against the machine. On the spiked slush preset, the total alcohol in the mix needs to land between 2.8 percent and 16 percent. A useful measure for spirits is 4 ounces of hard alcohol for every 24 ounces of total mix.

If the mix goes over the limit, the temperature lights chase upward one at a time and the unit beeps once a minute. The fix is dilution: add 1/4 cup of water, soda, or seltzer for every 8 ounce serving, press the preset once to reset, then press it again to restart. Wait 30 minutes and repeat if the batch is still thin. If the vessel is already full, dispense a glass first to make room.

Start cold and stay between the lines

Warm liquid is slow liquid. A mix that goes in at room temperature can take far longer to firm up than the same mix cold from the fridge, so chill everything before it goes in. Hot ingredients should never go into the vessel at all.

Fill matters just as much. Keep the liquid between the minimum and maximum lines on the vessel, which means at least 16 ounces and no more than 64 ounces. Below the minimum there is too little liquid to churn properly, and above the maximum the mix is crowded, expands as it freezes, and struggles to freeze evenly.

Your kitchen plays a part too. Run the machine indoors, and not in a room hotter than 100 degrees Fahrenheit. A hot room fights the cooling system the whole way and can turn a borderline mix into one that never gets there.

Give it time, then adjust the temperature

A batch is not late just because it is not ready in ten minutes. Depending on the volume, the ingredients, and the starting temperature, drinks can take up to 60 minutes to reach a proper slush.

If the texture is still not there after 60 minutes, raise the temperature control by one level using the up arrow, then wait 10 to 15 minutes and look again. If it is still too thin, go up one more level and repeat. Small steps beat big ones here, because each level needs time to show in the texture. Spiked drinks live at the cold end of the range, so a cocktail mix may need the highest levels before it firms up.

If you overshoot and the slush turns too thick to pour, do the reverse: lower the temperature control by a level or two and add 1/2 cup of liquid while it runs.