Which compound is toxic and not suitable for wiping down surfaces before painting?

Aromatic naptha is indeed considered toxic and not suitable for wiping down surfaces before painting. This compound contains a variety of hazardous volatile organic compounds (VOCs) that can pose significant health risks when inhaled or absorbed through the skin. Its use can lead to various adverse effects, including respiratory issues and skin irritation, and it may release harmful fumes that could also affect the environment.

In contrast, compounds like linseed oil and boric acid are not typically categorized with the same level of toxicity. Linseed oil is commonly used as a drying agent and is more benign in terms of health risks, while boric acid is often utilized for its insecticidal properties and has a relatively low toxicity profile for general use. Aliphatic naptha, although it should still be used with caution, is generally less toxic than its aromatic counterpart and is sometimes employed in cleaning applications due to its ability to effectively dissolve oils and paints.

Given these considerations, aromatic naptha stands out as the compound that poses the greatest health risks, thus making it unsuitable for surface preparation prior to painting.