Yes, it will get solidify if you leave it out. So, remember to keep the slime in air tight cups (included in the product) to ensure it can be reused over time.

Maybe you get the glue or activator ratio wrong. Try adding 2 or 3 drops of activator and repeat the kneading process. You can add any add-ons (snow powder, foam balls, candy wrappers, etc.) and it will not stick.

If the slime gets on any material, wet it with vinegar to break up the gel, then wash the material with soapy water or foam type upholstery cleaner.

To make sure your slime is super stretchy, you can try adding some clay after making the slime. Slime needs to be played with and absorb the heat from your hands to get truly stretchy.

In addition to following the steps in the instructions, you need to make slime in an environment with a temperature of 20 to 45°C (68-113°F), it will form easily; if the ambient temperature is lower than 20°C, it is not conducive to making slime.