Weathering 101: Pin Washes, Filters, and Dry-Brushing Explained

A factory-fresh paint job looks great on the shelf, but real vehicles, aircraft, locomotives, and ships pick up dust, grime, fading, and wear the moment they leave the factory floor. Weathering is the set of techniques modelers use to recreate that lived-in look, and while it can seem intimidating from finished examples online, the core techniques are more approachable — and more forgiving of mistakes — than they first appear. All three of the techniques below share the same underlying idea: thinned paint, applied deliberately and in a specific way, does something a straight coat of full-strength paint can't.

Pin washes: settling paint into recessed detail

A pin wash is a heavily thinned paint — often diluted well beyond normal painting consistency, commonly somewhere in the range of 1:3 to 1:6 paint to thinner — applied with a fine brush directly into panel lines, rivets, and other recessed detail. Capillary action pulls the thin liquid along the recess, and once it dries, it leaves a subtle dark line that makes flat detail read as three-dimensional under normal lighting, the same way real grime and shadow naturally collect in a panel gap. The most common beginner mistake is applying the wash too thick, which floods the surrounding flat surface instead of staying contained in the recess; the fix is simply thinning further and applying more passes rather than trying to get full coverage in one go.

A worked example: three wash strengths side by side

Run the same 10 mL batch through the weathering wash ratio calculator at three different ratios and the difference in how heavily each one flows is immediately visible in the numbers. At a moderate 1:3 ratio, 10 mL splits to 2.5 mL of paint and 7.5 mL of thinner — about 50 drops of paint against 150 of thinner, using the calculator's default 20 drops per mL. Thin that same batch to a subtler 1:6 and the split moves to 1.43 mL of paint against 8.57 mL of thinner, roughly 29 drops to 171. Go the other direction to a heavier 1:2 mix, closer to what a first pin wash on high-contrast panel lines might call for, and it's 3.33 mL of paint to 6.67 mL of thinner — 67 drops to 133. The paint fraction roughly doubles between the lightest and heaviest of these three ratios, which is exactly the kind of difference that's easy to eyeball wrong by pouring "a splash" of thinner into "a bit" of paint, but is trivial to get right and repeat exactly once you have the drop counts in front of you.

Filters: shifting the overall tone

Where a wash targets specific recessed lines, a filter is an extremely thin, semi-transparent layer of color applied across a broad area to subtly shift its overall tone — warming up a panel that looks too cool, or adding a hint of another color that ties a model's palette together. Filters are typically even more diluted than washes — a ratio around 1:8 rather than a wash's typical 1:3 to 1:6 — applied in thin, uneven coats that are meant to be barely perceptible individually but add up to a noticeably richer finish. Because the effect is so subtle, filters are easy to underdo (which is safe) and easy to overdo if you're not checking the result after each pass dries; building up gradually is far more forgivable than applying too much at once and trying to strip it back off.

Filters and washes are really the same tool used at different strengths and for different purposes, which is worth keeping in mind if a filter isn't behaving the way you expect. A filter spread thin across a whole panel with a soft, dry-ish brush behaves very differently from the same paint pooled into a panel line by capillary action, even at a similar dilution — the technique (how and where the paint is applied) matters as much as the ratio itself.

Dry-brushing: picking out raised detail

Dry-brushing works almost opposite to a wash: instead of a thinned liquid settling into recesses, a brush loaded with a small amount of thicker paint, then wiped nearly dry on a paper towel, is dragged lightly across a model's surface. The remaining trace of paint catches only on raised edges, rivet heads, and high points, picking out detail with highlights the same way real-world wear polishes the highest points of a surface first. A common mistake is not wiping the brush dry enough before starting, which deposits solid color instead of the intended light dusting — when in doubt, wipe the brush on a paper towel until it looks almost empty, then test on scrap before touching the model.

Brush choice matters more for dry-brushing than for washes or filters. A stiffer, slightly worn brush actually works better than a soft new one, because stiffer bristles deposit paint more selectively on the highest points rather than flexing into recesses the way a soft brush can. Many modelers keep a dedicated "dry-brush only" brush that's past its best for regular painting rather than switching a good detail brush between wet techniques and dry-brushing.

Matching weathering intensity to scale and subject

How heavy a hand to use isn't just a matter of taste — it scales with the model itself. A large 1:18 or 1:24 model has more surface area and more physical distance between panel lines, so a wash or dry-brush pass that reads as subtle up close can look almost invisible from normal shelf-viewing distance; these larger scales generally tolerate, and often benefit from, a slightly heavier hand. A small 1:64 or 1:87 model is the opposite case: panel lines are already close together and fine detail is compressed into a small area, so the same heavy wash that suited a 1:18 model can turn into a muddy, overdone mess at 1:64. When moving between scales, treat a technique you've calibrated on one as a starting point to retest, not a setting to reuse directly.

Combining techniques in the right order

Most finished weathering jobs layer these techniques rather than relying on just one. A typical order works from broad and subtle toward small and sharp: base coat and any filters first to establish overall tone, then washes to define recessed detail, then dry-brushing last to pick out highlights on top of everything else. Working in this order means each layer builds on a stable foundation rather than risking disturbing earlier work, and it mirrors how weathering effects actually accumulate on a real vehicle over time — overall grime and fading first, with sharper wear appearing on the parts that get touched or exposed the most.

It's worth letting each layer dry fully before starting the next one, even when the temptation is to keep working while the model is in front of you. A wash that hasn't fully cured can lift or smear when a filter or a dry-brush pass goes over it, which undoes the very control that makes these techniques worth doing in stages in the first place. Drying times vary by paint and thinner, but when in doubt, waiting longer costs you nothing; disturbing a layer that wasn't ready usually costs you redoing it.

Working paint into fine detail without flooding it

Fine detail brushes make a real difference for pin washes specifically, because the wash needs to reach into a panel line without depositing so much liquid at once that it overwhelms the recess. A brush with a genuinely fine point, loaded lightly and touched to one end of a panel line rather than dragged along its whole length, lets capillary action pull the wash the rest of the way on its own — which is both more controllable and, in practice, less wash per pass than trying to paint the whole line in one continuous stroke.

Removing a wash that's gone wrong

Because a wash is just heavily thinned paint, a pass that's too dark, too heavy, or has flooded outside the panel line is rarely a disaster — it's usually still workable while wet. A clean brush dampened with plain thinner (not more paint) and drawn along the flooded area lifts excess wash back out of the recess without removing what's already settled into the panel line itself, since the thinner in the wash and the correcting thinner are the same liquid and don't fight each other on the surface. Once a wash has fully dried, correcting it is more work — usually another, more careful pass rather than trying to lift the dried layer — which is one more reason to check a wash's strength on scrap before it's on the model and has had time to set.

Practice on something disposable first

Every one of these techniques rewards testing on a spare part, an old built kit, or a cheap practice piece before committing to a model you care about. Thinning ratios, drying times, and how a specific paint and thinner combination behaves all vary enough between brands that a technique described online won't transfer perfectly without a little hands-on calibration on your own materials first. This introduction covers what each technique does and how the three fit together; for a closer look at deliberately dialing a wash's strength up or down to control exactly how strong the finished effect reads, see the guide to controlling the weathering wash effect. Washes and thinners are solvent-based products, so the same ventilation, gloves, and no-open-flame precautions covered in the airbrush versus brush paint ratio guide apply here too.