Natural wood
Grain character, moisture condition and resin behaviour influence preparation, sanding and whether a stain-based or colour-based structure is appropriate.
TECHNICAL GUIDE · COATING SYSTEM ARCHITECTURE
The Lotus Coating Layer System: Filler, Primer, Color and Finish
Substrate · Preparation · Filler · Primer · Colour · Decorative · Clear
A finished coated surface is rarely the result of a single product. It is the result of a coating system — a sequence of functional layers selected for the actual substrate, the required appearance and the factory's production process.
The layer structure is defined per project — from the substrate, the finish target and the factory's production process.
01 / 07System Thinking
Why Coatings Are Specified as a System
On a manufactured product, the visible finish is the last step of a system that begins at the substrate. Each layer performs a distinct function — preparing the surface, building adhesion, establishing colour, creating decorative character and completing the finish. Specifying the coating as a system, rather than as a single product name, is what makes the result reproducible in production.
Substrate condition and surface preparation
Adhesion between the material and the system
Surface build where the substrate requires it
Colour foundation and approved colour reference
Decorative appearance where the design requires it
Final finish, drying and production handling
The layer structure is designed around the substrate and the required finish — not around a fixed universal recipe.
02 / 07Substrate First
Start With the Substrate
Layer selection starts with the actual material, not with the product line. The same target appearance can require a different coating structure on different substrates — because each material brings its own surface condition, absorption behaviour and adhesion requirements.
MDF and engineered wood
Uniform faces but absorbent cut edges — edge condition can change how primer and colour layers are built compared with solid wood.
Veneer
A thin decorative surface over a core — sanding depth and surface build are controlled differently from solid wood.
Composite
Surface condition can include pinholes or moulding variation — primer selection and surface build are evaluated against the actual surface.
Steel and iron
Metal substrates introduce corrosion and adhesion considerations that do not exist on wood — the primer layer carries a different function.
Concrete and cement
Absorption, moisture and surface condition vary — preparation and primer selection are evaluated against the actual surface.
Cement board / fiber cement board
A manufactured board with its own surface character — used in construction and decorative applications where a defined finish is required.
The substrate determines what the coating system must accomplish — which is why Lotus evaluates the material before proposing a layer structure.
03 / 07Layer by Layer
The Functional Layers
A Lotus coating system is described as a sequence of functional layers. Not every system uses every layer — each layer below is included only where the substrate, finish target and production process require it.
01
Surface Preparation
Foundation for every layer that follows
Cleaning, sanding, and removing contamination so the first coating layer can perform on a defined surface. Preparation is substrate-specific — sanding practice on wood, edge treatment on MDF, contamination removal on metal, and surface condition on cement-based materials are each handled differently. Where relevant, moisture condition is part of the evaluation.
02
Filler / Putty Layer
Surface build where the substrate requires it
Filling addresses pinholes, open pores, joints or surface imperfections so subsequent layers sit on a more uniform surface. It is a corrective layer, not a default one — a well-prepared substrate may not need it, while an open-pored or damaged surface may depend on it. Within the Lotus wood system, products such as Lotus Filler, Wood Filler and Wood Matic serve this function.
Lotus Filler · Wood Filler · Wood Matic
03
Primer / Adhesion Layer
Adhesion and substrate isolation
The primer connects the substrate to the coating system. Depending on the material it may promote adhesion, isolate the substrate (for example, blocking resin behaviour on certain woods), provide corrosion protection on metal, or create a uniform base for colour. Examples within Lotus systems include Wood Primer and Sanding Sealer on wood, Metal Coat Primer on steel and iron, and PUD-779 Primer where that system is specified.
Wood Primer · Sanding Sealer · Metal Coat Primer · PUD-779 Primer
04
Base Colour Layer
Colour foundation and visual base
The colour layer establishes the approved appearance — whether a transparent stain that keeps the grain visible or a solid colour that hides the substrate. Colour is developed against an approved colour reference rather than a screen or catalogue image, and the approved sample becomes the basis for production reproduction.
05
Decorative / Wood-Grain Layer
Appearance where the design requires it
Some systems include a dedicated decorative layer — most visibly in wood-look finishes, where a grain pattern and visual depth are created over the base colour. Application technique varies by system and can include brush or scratch-grain work and spraying. This layer exists only where the design calls for a decorative effect — it is not part of a standard solid-colour system.
06
Sealer / Topcoat / Clear Coat
The final functional surface
These terms describe related but distinct functions. A sealer typically closes and levels a layer within the system (for example between coats). A topcoat is the final applied finish. A clear or protective coat preserves the colour or decorative layer beneath it. Which of these a system uses — and in what combination — is defined by the finish target, end use and project requirements. Examples within Lotus systems include Acrylic Lacquer, water-based Polyurethane topcoats, PUD clear finishes, and the Shield and Hard Shield products used in wood-look systems.
Acrylic Lacquer · Polyurethane · PUD · Shield / Hard Shield
07
Drying, Curing and Inspection
The process steps between the layers
Between and after the layers, the system depends on drying and curing behaviour, sanding between coats where specified, and inspection against the approved reference. These steps are defined per product and system — they are part of the specification, not an afterthought.
04 / 07System Structures
Example System Structures
The structures below illustrate how the layer logic changes with the substrate and the finish target. They are system architecture examples — not fixed recipes, and not every step applies to every project.
Natural wood
Preparation → Filler where required → Primer / Sealer → Stain / Colour → Clear finish
MDF / veneer
Preparation → Filler / Primer where required → Colour / Stain → Finish
Composite
Preparation → Substrate-specific primer → Colour / Topcoat → Clear where required
Steel / iron wood-look
Preparation → Anti-rust / adhesion primer → Base colour → Grain layer → Wood-look finishing layer → Protective clear where required
Cement / cement board wood-look
Preparation → Primer / Base → Wood-look decorative layers → Shield / protective finish where required
The confirmed layer structure is defined per project after substrate evaluation — these examples describe selection logic, not universal Lotus recipes.
05 / 07Decision Framework
Layer Selection Decision Framework
The questions below are the practical inputs to defining a coating system. They are the same inputs Lotus uses when evaluating a new product or factory requirement.
What is the substrate?
Material, construction and any substrate-specific constraints such as absorption, edges or corrosion exposure.
What is the substrate condition?
New or aged surface, pinholes or imperfections, contamination, and moisture condition where relevant.
Is surface filling required?
Whether pores, joints or imperfections need a corrective layer before the coating build begins.
Is a primer required — and which function?
Adhesion, isolation, corrosion protection or surface preparation — the primer's job differs by substrate.
What appearance is required?
Transparent stain, solid colour, decorative grain or a specific approved reference.
Is a decorative or grain layer required?
Only where the design calls for wood grain, pattern or visual depth — not part of a standard colour system.
What final finish is required?
Sealer, topcoat and/or clear coat — selected against the finish target, end use and project requirements.
What application method is used?
Spray, brush or roller — and whether the system structure is 1K or 2K, which changes mixing and workflow.
What drying and handling conditions exist?
The factory's real drying windows, between-coat handling and packing schedule.
How will the system be validated in production?
Sample approval, factory trial and reproduction against the approved reference — before the system is deployed.
06 / 07Specification Principle
Not Every System Has Every Layer
There is no single universal Lotus coating recipe. The number and function of layers are defined by the substrate, the finish target and the production process — and confirmed through sampling and factory trial.
A solid-colour system on a well-prepared substrate may need no filler and no decorative layer.
A wood-look system on steel carries layers that a clear finish on natural wood does not — and vice versa.
More layers are not automatically better; every added layer adds process time, handling and variables to control.
The correct question is which layers this product needs — not how many layers a system can have.
07 / 07Questions
Coating System Questions
Not universally. Primer selection depends on the substrate and what the system must accomplish — adhesion, isolation, corrosion protection or surface preparation. The requirement is confirmed during substrate evaluation rather than assumed.
No. Filler addresses pinholes, open pores and surface imperfections where they exist. A well-prepared surface may proceed directly to primer or sealer — filler is a corrective layer, not a default one.
A sealer typically closes and levels a layer within the system, a topcoat is the final applied finish, and a clear or protective coat preserves the layer beneath it. They are related functions rather than interchangeable terms — which of them a system uses depends on the finish target and project requirements.
No. A wood-look finish adds a decorative layer — the grain or pattern step — on top of the base colour, plus the substrate-specific preparation and primer the material requires. A standard solid-colour system has no decorative layer.
Not without evaluation. The same target appearance can require a different structure on wood, composite, steel or cement — because each substrate changes the preparation, primer function and surface build the system needs.
1K and 2K describe how the coating components are supplied and cured, which can apply to different layers within the same system. Layer structure defines what each coat must do; the 1K/2K decision defines how the products in that structure behave in production. See the 1K vs 2K specification guide for the selection logic.
Technical Inquiry
Request a Coating System Evaluation
Send the product and substrate information, target finish, application method and production context. Lotus can evaluate the requirement and propose a layer structure for sampling and factory trial.
- Product type and substrate
- Surface condition if known
- Target finish or approved reference
- Application method if known
- Production location in Vietnam
- Technical documentation requirements