What will happen if too little hardener is used when applying filler?

Using an insufficient amount of hardener when applying filler compromises the chemical reaction necessary for curing. Filler relies on a specific ratio of resin and hardener to achieve the desired hardness and adhesion properties. When there is too little hardener, the filler will not cure properly, resulting in poor bonding to the metal surface. This inadequate adhesion can lead to issues such as peeling, cracking, or the filler not staying in place during subsequent treatments such as sanding or painting.

Maintaining the correct mix ratio is crucial for ensuring that the filler not only hardens appropriately but also bonds securely to the underlying metal, contributing to the overall integrity and durability of the repair work. When the appropriate hardener is used, the filler will cure fully, ensuring a strong and lasting bond to the surface it is being applied to.