What happens if too much hardener is added to filler?

• A. It may cure too quickly and become brittle
• B. It will not cure at all
• C. It becomes soft and gummy
• D. It will expand excessively

Answer: (A)

When you mix two-part body filler, the hardener starts a chemical reaction that makes the filler hard. The amount of hardener controls how fast this reaction happens and how the cured film forms. If you add too much hardener, the reaction goes too quickly and the filler cures in a very short time, leading to a film that is highly crosslinked. That rapid cure and dense crosslinking make the material very hard and brittle, so it’s prone to cracking or chipping when it’s flexed or under impact.

This isn’t about curing failing altogether; it’s about curing too fast and ending up with a brittle finish. The option about softness or gumminess would come from under-curing (not enough hardener) rather than excess hardener. Expansion isn’t a typical outcome of over-drying filler either, so that choice doesn’t fit with how these materials cure.