2025-08-23 by Cellulose Ether

Here’s a clear and practical explanation for you 

How to Make Perfect Wall Putty with HPMC (Hydroxypropyl Methylcellulose)

Wall putty is used to smoothen walls and provide an even surface for painting. The secret to making high-quality putty lies in choosing the right additives—HPMC is one of the most important.

Why HPMC in Wall Putty?

HPMC cellulose ether acts as a water-retaining agent, thickener, and workability improver. It ensures smooth application, prevents cracks, and extends open time.

Basic Formula for Wall Putty (Powder Mix)

  • White cement: 30–50%

  • Calcium carbonate (filler): 40–60%

  • HPMC (0.2–0.5%): Improves workability, water retention, crack resistance

  • Starch ether (optional, 0.05–0.1%): Enhances smoothness and anti-sag

  • Polymer powder (optional, 2–5%): Improves adhesion

  • Additives: Dispersing agent, defoamer, preservatives (as needed)

Step-by-Step Guide

  1. Dry Mix the Powders

    • Combine white cement and fillers (calcium carbonate, dolomite, etc.) evenly.

    • Add HPMC and optional additives in dry form.

  2. Ensure Proper Dispersion of HPMC

    • HPMC must be well-dispersed in dry mix to avoid clumping.

    • Using a high-speed mixer helps achieve uniform distribution.

  3. Add Water During Application

    • Mix the dry powder with clean water on-site until a smooth paste forms.

    • HPMC will absorb water, swell, and thicken the paste, giving it the right consistency.

  4. Adjust Consistency

    • If the paste is too thick, add a little water.

    • If too thin, check the dosage of HPMC or fillers.

  5. Apply on Walls

    • Spread evenly with a trowel or putty knife.

    • Thanks to HPMC, the putty will stay workable longer, bond better, and resist cracks.

Tips for Perfect Putty

  • Use high-viscosity HPMC (50,000–75,000 cps) for wall putty—gives better water retention.

  • The dosage is small (usually 0.2–0.5%) but has a big effect.

  • Store in dry conditions to prevent HPMC or powders from absorbing moisture.

Result: Smooth, workable, crack-free wall putty that provides the perfect base for painting!

 

Perfect  Let’s make it practical and ready-to-use. I’ll give you a standard wall putty formula with exact percentages, then a step-by-step mixing guide you (or your factory) can follow.

Standard Wall Putty Formula (by weight)

Ingredient Percentage (%) Function
White Cement 35–40% Binder, strength
Calcium Carbonate (CaCO₃) 45–55% Main filler, smoothness
Talc / Dolomite (optional) 5–10% Extra smoothness
HPMC (Hydroxypropyl Methylcellulose) 0.3–0.5% Water retention, workability
Starch Ether (optional) 0.05–0.1% Improves spreadability
Redispersible Polymer Powder (RDP) 2–3% Adhesion, flexibility
Preservatives / Defoamer 0.1–0.3% Prevents mold, foaming

If you want a basic economy formula, you can use just:
White cement + Calcium carbonate + HPMC

Step-by-Step Mixing Instructions

1. Dry Mixing (Factory / Large Batch)

  • Put white cement and fillers (CaCO₃, talc) into a high-speed mixer.

  • Add HPMC powder slowly to ensure even distribution.

  • If used, add RDP, starch ether, defoamer, preservatives.

  • Mix for 10–15 minutes until fully uniform.

  • Pack into bags (20–40 kg) for storage.

2. Preparation for Application (On Site)

  • Mix 1 part wall putty powder with 0.35–0.40 parts clean water.

  • Add powder to water (not water to powder) while stirring.

  • Stir until smooth paste, no lumps.

  • Rest the mix for 5 minutes, then stir again for best performance.

3. Application

  • Apply evenly with a putty knife / trowel.

  • First coat: thin layer (1 mm). Let it dry for 6–8 hours.

  • Second coat: another thin layer (1 mm).

  • After drying, lightly sand for smooth finish.

Tips for “Perfect” Putty

  • Use HPMC viscosity: 50,000–75,000 cps (better water retention, smoothness).

  • Dosage looks tiny (0.3–0.5%), but it changes the whole performance.

  • Don’t add too much HPMC → may cause slow drying and sticky surface.

  • Always add powder into water when mixing, not the other way.