Thinner Selection by Paint Type (Resin System):

• Water-Based Paints (Plastic & Acrylic): The thinner is water.

• Oil-Based Paints (Alkyd Resins): Requires an Oil-Based Thinner (often called Synthetic Thinner).

• Nitrocellulose-Based Paints (commonly known in Iran as “Instant-Dry” Paints): Require Nitrocellulose Thinners.

• Other specialized types include: Epoxy Thinner for epoxy paints, Baking Thinner for stoving paints, and Polyurethane (P.U.) Thinner for polyurethane paints.

Selecting the correct thinner for a paint category is the first critical step. Subsequent steps involve meeting user expectations, which include:

• Drying Time: The speed at which the user requires the paint to dry, which primarily depends on the thinner’s evaporation rate.

• Surface Smoothness: A suitable thinner results in a smooth, uniform surface after application.

• Adhesion: The thinner’s ability to properly dissolve the paint itself and interact with the underlying coat directly influences final adhesion.

• Gloss Finish: The thinner’s solvency power affects how well the resin is dissolved, which impacts the final gloss level of the dried paint film.

As explained, so-called “Instant-Dry” thinners (a common term in Iran) are technically Cellulosic Thinners, used for nitrocellulose-based paints. These thinners play a vital role in determining application quality.

All instant-dry thinners are suitable for nitrocellulose paints and lacquers, but the specific choice varies based on customer preference and the intended application. These thinners are composed of:

• Active Solvents: Solvents that can dissolve nitrocellulose on their own (e.g., esters, ketones).

• Latent Solvents (Co-solvents): Solvents that do not dissolve nitrocellulose alone but enhance the solvency power of the active solvents.

• Diluents: Added to the formulation as needed, primarily to adjust cost and volatility.

The difference between various instant-dry thinners lies in their formulation and price. A thinner with a higher proportion of active solvents is a stronger solvent, possesses better performance properties, is typically classified as a premium-grade product (with a higher code/grade), and commands a higher price. Less expensive thinners provide the basic functions of a cellulosic thinner, but their performance should be judged accordingly.