How to determine if the material of a paint can is suitable for oil-based paint?

Step 1: First, directly distinguish the material type to initially determine compatibility.

The compatibility of mainstream materials with oil-based paints is clear, so you can directly filter them first:

✅ Materials suitable for oil-based paints: Tinplate, galvanized steel sheet, 304/316L stainless steel. These materials are resistant to oil solvent corrosion and can also isolate air, preventing the rapid evaporation of oil-based paint solvents, making them the preferred materials for oil-based paints.

✅ Qualified plastics in special cases: Engineering-grade PE/PP plastics labeled as solvent-resistant and oil-resistant are also suitable for oil-based paints.

❌ Materials unsuitable for oil-based paints: Ordinary low-priced plastics (non-solvent-resistant PE/PP), ordinary sheet metal without anti-rust coating. Ordinary plastics will be corroded and swollen by the solvents in oil-based paint, and may even release impurities that mix into the paint, causing the paint to be unusable; untreated sheet metal will rust and discolor, contaminating the oil-based paint.

Step Two: Uncertain Material? 3 Simple On-Site Verification Methods

1. Plastic Can Verification Method: Take a small amount of the oil-based paint to be filled and drip it onto an inconspicuous spot inside the paint can. Observe after 24 hours: If the plastic surface does not become sticky, deformed, or show signs of dissolution, the material's oil resistance is acceptable and it can be used. If it softens, becomes sticky, or changes color, it is not corrosion-resistant and should not be used to fill oil-based paint.

2. Metal Can Verification Method: Check if the can surface has a complete anti-rust coating: Tinplate and galvanized steel surfaces have a dense anti-rust protective layer. Scraping the inside with a hard object should not easily expose the underlying rust, indicating it is acceptable. If black rust is directly exposed after scratching, or if localized rust has already appeared, the anti-rust treatment is inadequate, and filling it with oil-based paint will contaminate the paint and it is unsuitable for use.

3. Professional third-party testing method: For large-scale industrial purchases, samples can be sent for professional oil resistance testing: According to the standard procedure of national standard GB/T9274, the sample of the can material is immersed in the corresponding oil solvent for 48 hours, and the abnormalities such as wrinkling, cracking, and peeling are observed. If there are no abnormalities, it is qualified.