Answer:
Glue and sawdust.
Step-by-step explanation:
Glue and sawdust are the substances that applied in wood to fill up cracks and grooves. You can use the glue and sawdust method to fill the gaps present in the wood. This method is a quick and easy solution that successfully fill up the gaps and grooves on the wood. The method of using this method is, first fill the gap with a small amount of wood glue, then rub sawdust into the gap which attached the saw dust with itself and the gaps are filled.