What is the best wash type for panel lines?

Enamel washes are widely regarded as the most controllable for panel line work because they remain workable for several hours and excess can be removed cleanly with white spirit without disturbing the underlying acrylic base coat (provided the base is fully cured under a gloss clear coat). Oil washes offer even longer working times. Acrylic washes are safer to use (no solvents) but dry quickly and are harder to remove cleanly.

Why do I need a gloss coat before washing?

A gloss clear coat creates a smooth, non-porous surface that allows the wash to flow freely by capillary action into recesses rather than being absorbed by a matt base coat. Without a gloss coat the wash will stain the surface unevenly and be almost impossible to remove cleanly. Apply a gloss coat and allow it to cure fully — at least 24 hours for solvent-based clears — before applying washes.

How does scale affect wash quantity?

Larger scales have physically wider and deeper panel lines at the model surface. A 1:35 AFV has panel lines roughly twice as wide as the equivalent 1:72 aircraft feature. Wider lines hold more wash by volume, so you need proportionally more wash on larger scale models to fill the recesses sufficiently.

What does capillary flow factor mean?

Capillary action is the phenomenon that draws liquid into narrow spaces — the same mechanism that pulls water up a paper towel. In panel line washing, the wash flows into recesses by capillary action. The capillary flow factor adjusts the calculated volume for surfaces where flow is restricted (heavily textured or oil-painted surfaces) or enhanced (very fine engraved lines that draw wash in aggressively).

How do I remove excess wash without damaging my base coat?

For enamel washes, dampen a cotton bud or flat brush with white spirit or odourless enamel thinner and gently stroke along the surface away from the panel lines. Never scrub. For oil washes, use the same technique while the paint is still pliable. For acrylic washes, work quickly and use a clean damp (not wet) brush. Always work in the direction of panel lines to leave residue where it reads most naturally.

Weathering Wash Mix Calculator — Paint-to-Thinner Ratio & Volume

Calculate the exact paint-to-thinner ratio, total wash volume, drying time and number of coats for oil, enamel and acrylic panel line washes.

Model Surface Area

Estimated total surface area to be washed — for a 1:48 aircraft this is typically 250–400 cm²

Model Scale

Scale determines physical panel line width, which directly affects how much wash is absorbed into the recesses

Wash Type

The paint chemistry determines dilution ratio, drying time and how excess wash is removed — enamel is most popular for panel lines

Panel Line Density

How many panel lines and recessed details the model has — more lines mean more wash is drawn into the surface and more coats are beneficial

How We Calculate This

This calculator determines how much weathering wash to mix based on the model surface area, panel line density, scale and wash chemistry. It then splits the total volume into paint and thinner components using the correct dilution ratio for each wash type.

The formula

Single coat volume = (Surface area / 100) × Density base rate × Scale modifier × Capillary flow factor × Surface tension coefficient

Total wash volume = Single coat volume × Number of coats

Paint volume = Total wash / (Dilution ratio + 1)

Thinner volume = Total wash − Paint volume

Density base rate — 0.4 ml/100cm² (light) to 1.4 ml/100cm² (heavy)
Scale modifier — ranges from 0.7× at 1:72 to 2.0× at 1:16
Dilution ratio — enamel 1:12, oil 1:8, acrylic 1:6 (paint to thinner)
Capillary flow factor — adjusts for surface texture and line depth
Surface tension coefficient — accounts for paint brand and thinner chemistry differences

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify quantities before purchasing materials.