LBA521
LBA521 thixotropic clear polyurethane sealer (primer)
Two-pack clear thixotropic polyurethane sanding sealer (Milesi). Excellent for electrostatic spraying, high build that fills the grain well, and it sands very easily. Thixotropy lets you build film on verticals without runs. Part A solids 41 %.
- sealing furniture and joinery in softwoods (pine, alder)
- sealer under PU lacquers on verticals and complex parts: chairs, legs, balusters, assembled furniture
- electrostatic spraying of chairs, table legs and spindle work
Mix calculator
Ask about LBA521
Answers are based on the LBA521 data and the products it mixes with.
Mixing matrix
- % by weight: 50 %official% by volume: 50 %official
Current Technocolor recommendation — standard choice.
LNB77 is the hardener for PU primers and matt lacquers (dealer: 25 ± 1 % solids; Milesi TDS: 23.4 ± 2 %, 0.963 kg/l, 12-month shelf life). Fixed ratio — weigh it, do not eyeball.
- LNB42Hardener% by weight: 50 %dealer
Alternative from the Belarusian Milesi dealer sheet (2021). Technocolor now lists LNB5/LNB77 — use LNB42 only if you already have it and your supplier confirms.
Milesi TDS LNB42: 0.975 kg/l, 26.6 ± 2 % solids, 12-month shelf life.
- % by weight: 10–30 %official% by volume: 10–30 %official
10-15 % for electrostatic and verticals (keeps the thixotropy); 20-30 % for air/HVLP spraying on flat panels for better flow.
LZC1026: universal, medium evaporation, for PU and NC at 18-22 °C (s.g. 0.850). LZC1051: PU 'extra' thinner, medium, for PU at 18-22 °C (s.g. 0.864). In hot weather Milesi's TDS prefers LZC941 (also medium evaporation, recommended for the warmer season) over LZC1026, but it is not officially listed for LBA521.
- LZC1026Thinner% by weight: 25 %dealer
Default figure from the Milesi dealer sheet (BY).
Sits inside the official 10-30 % range.
| Role | Material | % by weight | % by volume | When |
|---|---|---|---|---|
| Hardener | LNB5 / LNB77 | 50 %official | 50 %official | Current Technocolor recommendation — standard choice.LNB77 is the hardener for PU primers and matt lacquers (dealer: 25 ± 1 % solids; Milesi TDS: 23.4 ± 2 %, 0.963 kg/l, 12-month shelf life). Fixed ratio — weigh it, do not eyeball. |
| Hardener | LNB42 | 50 %dealer | — | Alternative from the Belarusian Milesi dealer sheet (2021). Technocolor now lists LNB5/LNB77 — use LNB42 only if you already have it and your supplier confirms.Milesi TDS LNB42: 0.975 kg/l, 26.6 ± 2 % solids, 12-month shelf life. |
| Thinner | LZC1026 / LZC1051 | 10–30 %official | 10–30 %official | 10-15 % for electrostatic and verticals (keeps the thixotropy); 20-30 % for air/HVLP spraying on flat panels for better flow.LZC1026: universal, medium evaporation, for PU and NC at 18-22 °C (s.g. 0.850). LZC1051: PU 'extra' thinner, medium, for PU at 18-22 °C (s.g. 0.864). In hot weather Milesi's TDS prefers LZC941 (also medium evaporation, recommended for the warmer season) over LZC1026, but it is not officially listed for LBA521. |
| Thinner | LZC1026 | 25 %dealer | — | Default figure from the Milesi dealer sheet (BY).Sits inside the official 10-30 % range. |
Percentages are per 100 parts of component A.
Characteristics
- Solids
- 41 %dealer
- Mixed solids %
- 27–36 %recommended
- Viscosity
- not publishedrecommended
- Density
- 0.95–1.05 kg/lrecommended
- Thixotropy
- yesofficial
- Electrostatic suitability
- excellent (отличная электростатичность)official
- Sandability
- excellent (отлично шлифуется)official
- Filling
- excellent filling (отличная наполняющая способность)official
- Drying · Conditions
- 20 °C, 65-70 % RH
- Drying · Dust-free
- 15–30 minrecommended
- Drying · Sand or stack
- 4–16 hrecommended
- Drying · Full cure
- 24–48 hrecommended
- Pot life
- 3–6 hrecommended
- Hardness
- not publishedrecommended
- Lightfastness
- not specified; clear PU sealer under topcoatrecommended
Application
Electrostatic
- Consumption
- up to 150 g/m²official
- Nozzle
- 0.28–0.33 mmrecommended
- Pressure · fluid
- up to 20 barofficial
- Pressure · air
- 1–2 barofficial
- Pressure · Typical fluid equipment
- 50–80 barrecommended
- Spray viscosity
- 18-22 s DIN4recommended
- Wet film
- 130–160 µmrecommended
- Coats
- 1–2 coatsrecommended
The thixotropic body holds on verticals — ideal for chairs and legs. Milesi makes dedicated electrostatic thinners LZC50/LZC13 (resistivity-controlled); the official list for LBA521 is LZC1026/LZC1051 — if the gun won't wrap or trips on current, check the mix resistivity.
Conventional spray
- Consumption
- 130–150 g/m²official
- Consumption (alt.)
- 120–150 g/m²dealer
- Nozzle
- 1.8–2 mmrecommended
- Pressure · air
- 3–4 barrecommended
- Spray viscosity
- 18-22 s DIN4recommended
- Wet film
- 130–160 µmrecommended
- Coats
- 1–2 coatsrecommended
- Flash-off
- 10–20 minrecommended
Gun distance 20-25 cm, 50 % overlap.
HVLP
- Consumption
- 130–150 g/m²official
- Nozzle
- 1.7–2 (typ. 1.8) mmrecommended
- Pressure · air · Inlet pressure
- 2–2.5 barrecommended
- Pressure · air · Cap
- ≤ 0.7 barrecommended
- Spray viscosity
- 18-22 s DIN4recommended
- Wet film
- 130–160 µmrecommended
- Coats
- 1–2 coatsrecommended
For HVLP thin towards 20-30 %; on a 1.5 mm tip this sealer goes on orange-peely.
Airmix (air-assisted airless)
- Consumption
- 130–150 g/m²official
- Nozzle
- 0.28–0.33 mmrecommended
- Pressure · fluid
- up to 20 barofficial
- Pressure · air
- 1–2 barofficial
- Pressure · Typical fluid equipment
- 50–90 barrecommended
- Spray viscosity
- 20-25 s DIN4recommended
- Coats
- 1–2 coatsrecommended
Airless
- Consumption
- 130–150 g/m²official
- Nozzle
- 0.33–0.38 mmrecommended
- Pressure · fluid
- 120–180 barrecommended
Not officially listed for LBA521; large flat panels only.
Process and compatibility
- Substrate preparation
- Dry timber (8-14 % MC), sanded P150-P180 (softwoods P180), dust-free. Stain/dye first if required and let it dry fully.recommended
- Wood moisture
- 8–14 %datasheet
- Goes under
- LGA531 / LGA532 / LGA533 / LGA534 / LGA535 / LGA536 / LGA20 / LGA21 / LGA210 / LGA22 / LGA84
- Sanding
- P280-P320 (P240 for a first coat on softwood), to an even matt surface; don't cut through on edges.recommended
- Temperature and humidity · Application
- 15–30 °Cdatasheet
- Temperature and humidity · Drying
- not below 15 °C; RH 50-70 % during dryingdatasheet
- Don'ts
- don't exceed 150 g/m² per pass
- don't alter the hardener ratio (fixed 100:50)
- don't apply below 15 °C or above 30 °C
- don't sand while the paper still clogs — let it dry longer
- don't use the mix past its pot life
Storage
- Storage temperature
- 0–35 °Cdatasheet
- Shelf life
- not published for LBA521; hardeners LNB77/LNB42 12 months from production (TDS)recommended
Safety: Two-pack solvent-borne material with an isocyanate hardener: spray booth with extraction, A2P2 respirator (or air-fed), gloves and goggles. Spark-proof equipment, no smoking. Hardener is moisture-sensitive — close tins tightly.
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).
- official: properties, methods/consumption, hardener LNB5/LNB77 50 %, thinner LZC1026/LZC1051 10-30 %
- dealer search: name 'Грунт полиуретановый прозрачный тиксотропный', manufacturer MILESI; product page itself 404
- Milesi BY dealer: max pore filling, softwoods (pine, alder), 120-150 g/m², solids 41 %, LNB42 50 %, LZC1026 25 %
- dealer: LNB77 hardener for PU primers and matt lacquers, solids 25 ± 1 %
- Milesi TDS LNB77 + general application/storage conditions
- Milesi TDS LNB42
- Milesi LZC thinner series TDS (LZC1026, LZC1051, LZC50, LZC13, LZC941)
- official application methods (airmix: up to 20 bar fluid, 1-2 bar air; airless up to 200 bar; electrostatic for chairs/legs/cots)
Not covered by the sources
- Dealer product page for LBA521 on t-colormarket.ru (/catalog/lkm/grunty_gruntovki/poliuretanovye_grunty/lba521/) returns 404 (re-checked 2026-10-05; only the search snippet exists) — no 'Все технические характеристики' (viscosity, pot life, drying times)
- No Milesi TDS for LBA521 found (faichim/edid-milesi/milesi.com probed)
- viscosity of part A (not published)
- density of part A (not published)
- pot life (not published; derived estimate only)
- drying times dust-free / sandable / full (not published; derived estimates only)
- packaging sizes and shelf life of LBA521 itself
- hardener LNB5 — no data found (no official/dealer page, no TDS)
- conflict: official hardener LNB5/LNB77 vs 2021 Belarus Milesi dealer LNB42 — both recorded, official preferred
- LZC1026 has no official Technocolor page or dealer listing (only Milesi LZC TDS, 1998 edition)
- not used in any official Technocolor finishing schedule (information/technology)
- not present in the Technocolor 2025-2026 catalog transcripts
- hardener LNB5 — re-checked 2026-10-05: no t-colormarket search hit, no faichim TDS (LNB5_IT.pdf not found)
- airmix fluid pressure: official methods page says up to 20 bar; real-world pumps often higher — both recorded