Which substance is used to thin gel-coat?

Acetone is commonly used to thin gel-coat due to its effective solvent properties. When gel-coat needs to achieve a more fluid consistency for application, acetone can dissolve certain resin components without significantly impacting the integrity of the gel-coat itself. This allows for a smoother application and better finish. Additionally, acetone evaporates quickly, which is advantageous during the application process because it minimizes the potential for drips and runs.

Using water as a thinner would not be appropriate, as gel-coat is a resin-based product, and water could compromise its curing and adhesion properties. Alcohol, while a solvent, is not effective for this purpose as it can also negatively affect the properties of the gel-coat. Hexane, on the other hand, is not a typical choice for thinning gel-coat and may not perform as well as acetone due to its slower evaporation rate and potential to not blend properly with the resin components.