Any consistency of slime can be made by varying the water-to-methyl-cellulose ratio. It can be made very thin (akin to silky water), medium (like sex lube), or even as thick as mayonnaise. At the extreme, it can even be made solid. Very few other substances allow the versatility of methyl-cellulose.

This white, powdery substance actually dissolves better in cold water than warm water. However, adding it directly to cold water can cause it to dissolve almost instantly, resulting in slimy clumps that contain dry powder. This can be avoided by stirring or mixing vigorously while gradually shaking the powder into the water.

Alternatively, using hot water will prevent the clumping and promote even disbursement of the powder grains into the water. As the water cools, the grains will will begin to actually dissolve and thicken the water. It is important to shake or mix the solution very frequently as it dissolves, or else you will end up with a thick layer of solid slime on the bottom of the container, with pain water on top. Shaking it will not mix it back up.

If you end up with a layer of solid slime, or with clumps, they can be dissolved with a hand mixer, resulting in perfectly-smooth slime.

To get a syrupy texture, mix about 5% methyl-cellulose to 95% water. This equates to about a heaping teaspoon in a cup of water, or 2 pounds of it in a normal-sized bathtub. Different grades of methyl-cellulose, and other factors, may affect its efficiency at thickening, as well as how quickly it finishes thickening. It is easy to dilute if it's too thick, and also easy to add extra powder to a mixture that is too thin: The initial thickness of the existing slime helps to keep the additional powder suspended while it absorbs water, so you won't need to heat it or mix it as virously.