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Sanding old coatings — practical guidance and quality checks

Sanding is intended to remove weak areas and increase adhesion, but must not overheat, polish or excessively weaken the substrate. The most important thing is to prepare the input conditions, the correct order and control the result before moving on.

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In brief Sanding is intended to remove weak areas and increase adhesion, but must not overheat, polish or excessively weaken the substrate. The most important thing is to prepare the input conditions, the correct order and control the result before moving on.
Budget friendliness 6/10

The higher the score, the lower the typical cost impact of this work stage.

Quality impact 8/10

The higher the score, the stronger this stage affects final quality and durability.

Ease of execution 6/10

The higher the score, the easier this stage is to complete correctly without too many dependencies.

In brief

Sanding is intended to remove weak fragments and increase adhesion, but it must not overheat, polish or excessively weaken the substrate.

The most important are the preparation of input conditions, the correct sequence and the control of the result before moving on next.

Goal and result of the stage

The "Grinding of old coatings" process is used to obtain a load-bearing surface that is clean, dry, even and compliant with the requirements of the next layer.

When to perform this step

This topic should be considered after dismantling and installation repairs, immediately before priming or applying the finishing layer.

The term results from technical dependencies. Doing it too early may result in damage to the finished work, and doing it too late may result in blocking access or requiring corrections.

What must be ready before start

Before starting, prepare: assessment of adhesion, moisture, absorbency, evenness and type of existing layers.

Materials, tools and documents

Typical materials and auxiliary elements: repair compounds, leveling mortars, cleaning and degreasing agents, crack strengthening materials.

Typical tools and equipment: spatula and scraper, sander with suction, level or patch, moisture meter matched to the substrate, vacuum cleaner industrial.

Correct execution order

  • Diagnose the load-bearing capacity, evenness, absorbency, humidity and type of existing layers.
  • Remove only weak layers, dirt and elements limiting adhesion.
  • Repair defects, cracks and unevenness with a material compatible with the substrate.
  • Leave the layers until set or dry in accordance with the product documentation.
  • Dust, clean and re-inspect the substrate before priming or finishing.

Execution conditions

Control temperature, humidity, ventilation, substrate condition and conditions specified by the manufacturer. Drying or setting times depend on product, layer thickness and conditions - do not shorten them based on surface appearance alone.

If different system instructions specify different requirements, adopt a more stringent condition or confirm with the manufacturer.

Quality Control

Perform the inspection in conditions appropriate for subsequent use and before covering the work with another layer.

  • the surface is evenly matt
  • the dust has been sucked out and removed
  • there are no deep scratches requiring repair
  • the substrate is load-bearing, clean and free from layers limiting adhesion

Safety and boundaries of independent work

Dust from old layers can be harmful. Limit its spread, use suction and respiratory protection. Do not sand material of unknown composition until it has been identified.

Common errors

  • sanding without suction
  • using too aggressive a grit
  • leaving dust in the pores of the substrate
  • applying new layers on dust, grease, weak paint or damp substrate

Difficulty, time and risk of errors

Execution variants

The substrate can be repaired locally, completely leveled or a new system solution can be created. The least invasive method only makes sense if the layers left behind are truly load-bearing.

What to do next after finishing

After preparing the substrate, apply the appropriate priming or layer provided by the system. Do not allow other works to re-dirty and damage the received surface.

Frequently asked questions

What does “Sanding old coatings” involve?

Sanding is intended to remove weak areas and increase adhesion, but must not overheat, polish or excessively weaken the substrate. The most important thing is to prepare the input conditions, the correct order and control the result before moving on.

What needs to be prepared before the "Sanding old coatings" stage?

Before starting, prepare: assessment of adhesion, moisture, absorbency, evenness and type of existing layers.

How can you verify that “Sanding old coatings” has been done properly?

Apply in conditions suitable for subsequent use and before covering the work with another layer. • the surface is evenly matt • the dust has been sucked out and removed • there are no deep scratches requiring repair • the substrate is load-bearing, clean and free from layers that limit adhesion

When should the "Sanding of old coatings" stage be entrusted to a specialist?

Outsource work when it involves active installations, structures, tightness, large or heavy components, or requires equipment and experience that you do not have. Don't study on a high value ready-made surface.