Koch-Chemie Heavy Cut "H9.02" Heavy Compound 1000ml

Polishing deep scratches out of the clear coat with the Koch-Chemie Heavy Cut H9.02

What is the Koch-Chemie Heavy Cut H9.02? A silicone-oil-free, coarse heavy compound with a cut rating of 9.0 and a gloss rating of 6.0 that machine-removes sanding marks down to 1,200 grit, deep scratches and weathering from the paint. Not a finishing polish, not for hot surfaces, and not for first-time polishers without a paint thickness gauge.

Koch-Chemie Heavy Cut H9.02 is a coarse heavy compound from Koch-Chemie with extremely uniform aluminium-oxide abrasives that machine away deep scratches, heavy weathering, paint overspray and sanding marks down to 1,200 grit from the clear coat. The abrasives break down during the polishing pass until they go translucent, and they keep cutting without burning through long enough to fully correct a panel without topping up.

That is what sets the H9.02 apart from old-school rubbing compounds: instead of big, coarse abrasives sitting in a wax carrier, the formula uses an evenly tuned particle-size spread that fractures as you polish and so automatically turns finer in the second phase of the pass. The result is a noticeably higher gloss at the same cut — fewer holograms after the first step, and often a starting point that only needs one follow-up stage. Within the Koch-Chemie polishes line-up, the H9.02 is the coarse correction stage that the finer finishing products build on top of.

• Cut rating 9.0 at a gloss rating of 6.0. At the same cutting power, the H9.02 leaves a noticeably cleaner gloss than the previous H9.01 (gloss rating was 5.0). It clears sanding marks down to P1200 grit in a single pass, and 50-micron scratches in the clear coat are levelled in two to three passes. After that step, a single follow-up with Micro Cut M3.02 is plenty in most cases.
• Silicone-oil-free and low-VOC to work with. With no silicone oil, there are no release-agent residues left in the paint to fight off a later ceramic coating or wet-on-wet sealant. Dust is practically zero when you work it right, because the aluminium oxide stays bound up in its breaking-down phase instead of flying off as powder.
• Two pad options for two severity levels. With the lambswool pad and a rotary, you pull sanding marks from P1200 to P2500 — maximum cut in minimum time. With the Heavy Cut Foam Pad Red in the 2024 build, you work sanding marks from P1500 to P3000 with dual-action polishers too, which makes life a lot easier for home detailers on GA6/DA-style machines.

Day-to-day from Detailing1: The most common mistake with the H9.02 is too little compound on the first pass and too much on every one after. When you prime a fresh pad, soak it right across the face — only then do the abrasives and the pad actually work together. From the second section on, 3 to 5 pea-sized drops per 40×40 cm panel is enough. Flood half the pad again on the second section and you end up with a layer of leftover compound residue that visibly drags the gloss down.

Cold paint. Soak the pad. Work it to translucent.

The Heavy Cut H9.02 only goes on cold, dry, contamination-free paint. Leftover contamination acts like grit and cuts fresh scratches.

Before every polishing round, the paint needs degreasing — best with an IPA cleaner from the prep range, to kill off any wax residue first. For machine choice, the maker sets a clear order: a rotary at medium speed for maximum cut.

The 2024 generation of the Heavy Cut pads now also lets you run them on dual-action polishers (DA polishers) — gloss stays comparable, the cutting time per panel goes up by about 20 percent. On the fresh pad you lay down an even film when you prime, spread it with finger pressure while the machine is off, then start at speed 1 to 2.

Working a crosshatch pattern with moderate pressure, you take a panel of 40 by 40 centimetres until the compound goes translucent. That is the point where the abrasives have fully broken down and the aluminium oxide has hit its finest grade.

Before that point the grit still cuts too hard and leaves a rough microsurface; past that point the pad runs dry and throws holograms. Two to three section passes per panel is the standard — on heavier defects, shrink the panel rather than stretch the working time.

You wipe the residue off with a clean, edgeless microfibre cloth — don't rub, wipe. Between panels, check the pad for saturation: if it is caked and shiny, loosen it up with a pad-cleaning brush; if it is smeared, swap it instead of fighting on.

Cut rating 9.0 clears P1200. Down to primer it won't.

The Koch-Chemie Heavy Cut H9.02 is a correction compound, not a repair. Anything that sits within the thickness of the clear coat — swirls from automatic car washes, buffer trails, sanding marks after wet-sanding down to P1200, water-spot etching, light bird-dropping etching, UV dulling — comes back in one to three passes. Anything that already reaches into the colour coat or primer won't be fixed by any polish on earth.

A paint thickness gauge is a must for serious work at cut rating 9. Modern OEM clear coats run between 40 and 60 microns, and a single H9.02 pass takes off 1 to 3 microns depending on pad and pressure. Work with no gauge and correct three times, and on jet-black clear coat you'll be down to the colour coat faster than you'd think — and then neither a finishing polish nor a sealant saves you, only a respray.

The honest limits: bitumen, tar and silicone stains don't react chemically with the aluminium oxide — for those you need a tar remover before you polish. Very soft Japanese clear coats (Toyota white, a few Mazda reds) can tip into the hologram phase fast with the lambswool pad, so here you're better off starting straight with the Foam Pad Red.

For fine correction of medium scratches the H9.02 is overkill — that's where the Fine Cut F6.01 is the right tool. When you've got deep defects: H9.02 as step one. When car-wash scratches down to P2500 are the problem: F6.01 is plenty on its own.

For serious correction, not the summer refresh.

The Koch-Chemie Heavy Cut H9.02 is the entry product for anyone who treats paint correction as a craft. For the occasional polisher it's overkill.

It's aimed at keen home detailers with a rotary or DA polisher, semi-pro reconditioners with a regular fleet workload, and shops prepping used cars for resale. If you refresh your new car once a year, you're a lot better off with a finer polish like the F6.01 or an all-rounder.

On cost, the 250 ml bottle is already the standard size for home use: at 2 to 3 millilitres per panel it lasts for around 100 to 125 panels, or roughly three to four full corrections — that works out to a material cost of about 14 to 17 cents per panel, priming the pad included. The 1-litre bottle pays off from the tenth correction job a year, and the 5-litre canister is the bulk size for outfits running flat out.

In day-to-day Detailing1 work the H9.02 never stands alone — it's step 1 in a two- to three-stage polishing system. The typical Koch-Chemie workflow: H9.02 on the Heavy Cut Pad Red for the coarse correction, Fine Cut F6.01 on the Fine Cut Foam Pad Yellow to even out the sanding structure, Micro Cut M3.02 to clear the holograms. Skip step 3 and you accept visible micro-sanding marks on dark paint. Over 87 percent of our H9.02 buyers add the F6.01 to the same basket — exactly for this reason.

But the biggest lever for a clean result is neither the polish nor the pad — it's the state of the paint before the first drop. Clean prep — clay bar, IPA wipedown, taping off the trim — saves a full polishing pass on average.

The best H9.02 tip from our bench, though, only comes at the end: after polishing, wipe the paint down with IPA again before you seal. The leftover oils from the pad are otherwise enough to cut the lifespan of a ceramic coating by 30 to 40 percent — and you only notice three months later. Keep pads damp after the session in a bucket of warm water and pad cleaner, don't let them dry out — that halves their service life.

Application of Koch-Chemie Heavy Cut H9.02

Prep, Prime, Polish to Translucency

Before the first drop hits the pad, the paint must be washed, decontaminated (clay bar if necessary), and degreased with an IPA cleaner. Wax residues or silicone remnants from prior treatments would otherwise react with the polish and cause irregular abrasive action.

When priming a fresh Heavy Cut Pad or lamb's wool pad for the first time, apply the polish evenly over the entire pad and massage it into the foam structure with your finger. From the second section onwards, 3 to 5 pea-sized drops per 40x40 cm panel are sufficient.

Place the machine onto the panel while it is switched off, distribute the polish evenly on speed 1 to 2, then increase to working speed (medium). Work in a cross-hatch pattern with moderate pressure until the polish becomes translucent — at this point, the aluminum oxide has fully broken down and reached its finest phase.

Two to three section passes per panel are standard. Wipe off residues with a clean, edgeless microfiber cloth. Coarse correction is followed by fine correction with Fine Cut F6.01 and finishing with Micro Cut M3.02.

Notes: H9.02 is not suitable for hot surfaces or direct sunlight — the pad would run dry and create holograms. Very soft Japanese clear coats should only be treated with the Red Foam Pad, not with lamb's wool. Before sealing, wipe with IPA; otherwise, the durability of the ceramic coating will suffer by 30 to 40 percent. Shake well before use. Store frost-free between 5 and 30 °C, use within 24 months after opening. Keep pads moist in pad cleaner water; do not let them dry out.