Before diluting any paint, the first step is to confirm two key factors: the paint type and the sprayer model, as both directly influence the optimal dilution ratio.
Water-based and latex paints: Clean water is the primary diluent, with a basic dilution ratio ranging from 5% to 20%.
Oil-based paints: Require specialized paint thinner, with dilution typically controlled between 10% and 30%.
Note: Recommended ratios may vary by brand and specific product formulation. Always use the manufacturer’s instructions printed on the product label as your primary reference.
Small handheld spray guns and pneumatic sprayers: Feature lower atomization pressure, so slightly thinner paint is recommended for smooth application.
High-pressure airless sprayers: Boast strong atomization and high operating pressure, allowing for reduced dilution. This adjustment prevents issues like sagging and insufficient coverage.
Fine-tune the ratio based on the manufacturer’s suggested parameters to achieve uniform atomization, smooth spraying, and high-quality film formation.
Proper pre-treatment of the original paint is critical to ensure consistent dilution results and protect spraying equipment.
Use a dedicated paint stir stick or electric mixer to stir the paint evenly. Start from the bottom of the can and mix upward to fully integrate pigments, resins, and additives. This step prevents uneven concentration, color variations, and settled lumps, ensuring an accurate dilution ratio and consistent finish during subsequent spraying.
After stirring, strain the paint slowly through a fine-mesh filter or clean gauze into a clean mixing container. This removes fine lumps, particles, and other impurities that could clog the sprayer nozzle or cause uneven atomization.
Important: Only add diluent after completing both stirring and filtration. This sequence improves spraying smoothness, extends equipment lifespan, and ensures a flat, flawless paint film.
Paint dilution must adhere to the "small batches, multiple additions" principle—never pour all the diluent at once. Follow these steps for precise ratio control:
Transfer the pre-treated original paint into a mixing container.
Based on the basic dilution ratio, calculate the estimated amount of diluent needed and add 1/3 of this amount slowly.
Stir continuously in the same direction with a stir stick to ensure full integration of the paint and diluent, avoiding local over-dilution.
After the first batch of diluent is fully mixed, check the paint’s fluidity. Gradually add smaller amounts of diluent, stirring thoroughly after each addition to maintain uniform consistency.
Keep stirring steadily in one direction to minimize air bubble formation until the paint reaches the viscosity required for your sprayer.
This process effectively prevents over-dilution (which causes sagging and poor coverage) and under-dilution (which leads to nozzle clogging and uneven atomization).
Use these intuitive observation methods to determine if the diluted paint has the correct viscosity for spraying:
Dip a stir stick into the mixed paint and lift it slowly.
Ideal viscosity: The paint flows down in a continuous, even stream without breaks, lumps, or splashing. The stream tapers gradually and breaks naturally within 5–10 seconds, with a steady dripping rhythm.
If the paint is too thick: It will drip in chunks, fail to form a steady stream, and cling heavily to the stir stick. Add a small quantity of diluent and mix the paint again thoroughly.
If the paint is too thin: It will run down quickly like water without forming a continuous stream, which can cause sagging and poor coverage. Adjust by adding a small quantity of undiluted original paint.
After passing the flow observation test, perform a small test spray. If there is no nozzle clogging and the atomization is even, the viscosity is confirmed suitable for formal spraying.
Never use non-compatible diluents (e.g., water for oil-based paint).
Do not arbitrarily alter the dilution ratio drastically to pursue faster flow, as this compromises paint film quality.
Avoid excessive stirring, which generates air bubbles that negatively impact film formation and spraying stability.
Over-dilution: Results in overly thin paint, leading to sagging, insufficient coverage, and substrate show-through.
Under-dilution: Causes high viscosity, easily triggering nozzle clogging, uneven atomization, obvious spray marks, and increased wear on spraying equipment.
Smooth, dense substrates (metal, plastic): Slightly thin the paint to enhance leveling and adhesion.
Porous, absorbent substrates (wood, concrete): Slightly thicken the paint to reduce excessive penetration, ensuring sufficient coverage and proper film thickness.
For all adjustments, follow the process of "small additions → thorough mixing → viscosity re-testing" to balance spraying performance, substrate compatibility, and equipment service life.