Skip to content
Dugan Design
← All products
+ Add with a base product
HardenersHardener

LNB21

LNB21 PU hardener (Milesi)

Milesi isocyanate hardener for two-pack polyurethane coatings. It has no page of its own on t-color.ru: the only official mention is on the LGA84 polyvalent PU lacquer (20 gloss) — 'LNB21/LNB42', 50 % by weight and 50 % by volume. Dealers (HolzCom/timb.ru, Art-Coating in Belarus) describe it as a 'hardener for PU primers and matt lacquers', the second component of PU materials, at 23 ± 1 % solids. No LNB21 TDS was found, and pot life / drying times for an LNB21 mix aren't published — the Milesi LGA84 TDS lists LNB77/LNB42 instead.

  • second component of LGA84 polyvalent PU lacquer (20 gloss) — 50 % by weight / 50 % by volume (interchangeable with LNB42)
  • per dealers — Milesi PU primers and matt PU lacquers (no products or ratios given beyond LGA84)

Ask about LNB21

Answers are based on the LNB21 data and the products it mixes with.

Questions and answers are stored to improve the assistant and prevent abuse; the question text is processed by Anthropic (USA). Privacy policy

Mixing matrix

  • LGA84base
    % by weight: 50 %official% by volume: 50 %official

    First official option for LGA84. Fixed ratio — 50 %. LNB42 is the alternative when you want more film build (dries slightly slower).

    Pot life and drying with LNB21 specifically aren't published — test the first batch on an offcut.

  • LBA* / LGA* (matt)base
    % by weight: 50 %recommended

    Only after checking with Technocolor — officially LNB21 is listed for LGA84 only.

Percentages are per 100 parts of component A.

Characteristics

Solids
23 ± 1 % by weight (hardener itself)dealer
Chemistry
isocyanate (NCO) hardener for 2K PU — type (aromatic/aliphatic) not publisheddealer
Drying · Conditions
20 °C, 65–70 % RH
Drying · Dust-free
10dealer
Drying · Touch-dry
30dealer
Drying · Sand or stack
4dealer
Drying · Full cure
handle/pack after 24 h, full chemical cure ≈ 7 daysrecommended
Drying · Forced drying (reference)
hot-air tunnel 25–60 °C — 1 hdealer
Moisture sensitivity
Isocyanate hardeners are sensitive to water.official
Mix solids (reference)
41 ± 2 % working mixdealer

Application

HVLP

Nozzle
1.5–1.8 (typ. 1.6)recommended
Pressure · air · Inlet pressure, min
2
Pressure · air · Inlet pressure, max
2.2
Pressure · air · at the cap, max
0.7
Pressure · air · Why ru
Стандартная настройка HVLP (давление на входе при нажатом курке, ≤ 0,7 бар на воздушной головке), как в практике мастерской владельца.
Spray viscosity
16–20 srecommended
Consumption
150official
Coats
1–2official
Recoat
2–4 h without sanding; later — sand firstdealer

Weigh the hardener in at exactly 50 % of the lacquer, stir, then thin with LZC1026 and let it stand 5–10 min. Only mix what you'll spray in 2–3 h.

Conventional spray

Nozzle
1.6–1.8recommended
Pressure · air
3–4recommended

Airmix (air-assisted airless)

Nozzle
0.23–0.28recommended
Pressure · fluid
10–20recommended
Pressure · air
1–2official

Curtain coater

Consumption
140official

On a curtain coater keep LZC1026 at 10 % max (LGA84 TDS).

Electrostatic

Consumption
140dealer
Nozzle
as airmix (09–11 thou)recommended

Process and compatibility

Temperature and humidity
apply 18–25 °C (not below 15 °C), 50–70 % RHrecommended
Don'ts
  • don't eyeball it — weigh it, 50 %
  • don't leave the can open: isocyanate reacts with air moisture, goes cloudy and thickens
  • don't use hardener that has gone cloudy, thick or skinned
  • don't mix with other hardener families (PC/AC) or swap LNB21 into other PU products without Technocolor's OK
  • don't use the mix after 2–3 h
  • don't spray below 15 °C

Storage

Shelf life
≈ 12 months in the sealed original canrecommended
Storage temperature
5–25 °C, dry, indoors, out of direct sunrecommended
Packaging
12.5 l (art. LNB21/12,5)dealer

Safety: Solvent-borne isocyanate hardener: highly flammable, isocyanate vapour/mist is a respiratory sensitiser. Spray booth, A2/P2 respirator or air-fed mask, nitrile gloves, goggles, spark-proof kit, no smoking. See the LNB21 SDS.

Mixed into

LBA527 / LGA84

Sources

Value tags: “official”, “dealer”, “catalog”, “schedule” are Technocolor data; “workshop” is from our own datasheets; “recommended” is our engineering estimate (hover to see the reasoning).

Not covered by the sources
  • No official t-color.ru page for LNB21 — official mention only on LGA84 ('LNB21/LNB42', 50 % w / 50 % v)
  • Not on t-colormarket.ru (search for LNB21 returns nothing, 2026-10-04)
  • No LNB21 TDS or SDS found (web-search budget exhausted this session; local PDFs and catalog transcripts contain no LNB21)
  • Isocyanate type (aromatic/aliphatic), density, viscosity, NCO content not published
  • Pot life and drying times for an LNB21 mix not published — figures given are LGA84 + LNB77/LNB42 references
  • Milesi LGA84 TDS (Sinay transcription) lists LNB77/LNB42, not LNB21 — conflict with the official page
  • Yellowing resistance of LNB21 mixes not published
  • Dealer claim 'for PU primers and matt lacquers' — no specific products/ratios beyond LGA84
  • Shelf life and storage temperature not published
  • Not in any official finishing schedule (information/technology) nor in the Technocolor 2025–2026 catalogue transcripts