Slime is a safe substance for children of all ages to explore, once the ingredients have been thoroughly mixed together.
Infants who are still in the stage of oral exploration should only play with slime under the close supervision of an adult, because swallowing large amounts of slime can cause problems similar to those caused by swallowing chewing gum.

Playing with slime is a great sensory activity.
Many infants enjoy touching slime, squeezing it in their hands and watching others stretch, bounce and roll their slime.
Talk to your infant about how the slime feels as they play with it.
As they play, use lots of descriptive words for how it feels, looks and smells- this will help them develop their emerging vocabulary.
Some older infants are learning to hold utensils and may enjoy holding tools that older children use to cut and shape their slime. Younger infants often explore these tools with their mouths, so be careful to ensure that the tools they explore orally do not have slime stuck to them.