Why is it necessary to add HPMC to putty powder during summer construction?

As the weather gets hotter in June, scraping putty in the heat is prone to many problems. MilaCellTM, the supplier of cellulose ether (HPMC|MHEC|HEC), summarizes the following problems and solutions that are prone to occur, which we hope will be helpful to you.

1. Putty chalking, peeling


When working under high and dry temperatures, moisture evaporates very quickly and if the putty does not have enough moisture for curing, it will easily chalk, which in turn will lead to peeling.


It is recommended to add MilaCellTM HPMC additive to improve the water retention and workability of the putty powder, and the quality of the putty powder will be significantly improved.

Another point is that in the case of exterior putty, after being washed by rainwater, its adhesion is reduced and it can easily fall off when reapplied. It is possible to add re-dispersible polymer powder(RDP) to increase the bonding.

Secondly, exterior wall putty construction should pay attention to moisturizing, avoid direct sunlight, moderate sanding, and full drenching more than 2 times after the surface becomes dry (increase the amount of HPMC).

2. Putty warped


The surface of the substrate is too dry or the temperature of the construction site is too high.


When the substrate is too dry, it should be moisturized and avoided in the middle of the day. The putty that has been turned over should be eradicated and re-scraped after applying the sealing material.

3. Putty cracking


A common reason is that every time the putty is applied, it is applied too thickly and the surface dries before the interior is dry.


If the putty is severely cracked, it needs to be removed and reapplied. If the joints are cracked, you should do a good job on the joints before applying the putty. The addition of MilaCellTM HPMC MH-100K can improve the quality of the putty powder.

4. Fast drying


If the temperature at the construction site is too high, the humidity around the site is too low, the ventilation is too strong, and the sunlight is direct, the reaction of the composite material in the putty will be accelerated.


Pay attention to the construction environment, avoid construction in high-temperature time, direct sunlight time, and control the construction site ventilation intensity. When the substrate is too dry and fast-absorbing, it is recommended to brush the interface agent or pre-wet the substrate (but no obvious water) before construction. Add hydroxypropyl methylcellulose to the putty powder to enhance the protection.

5. Putty bubbling


The temperature is too high and the substrate is too dry, causing the putty to dry quickly, resulting in bubbles.


Add MilaCellTM HPMC to the putty, mix thoroughly and apply at the proper temperature. If there are air bubbles when scraping the putty, press repeatedly after the surface is dry to eliminate the bubbles.

The main problem of applying putty in summer is to solve the problems of sun protection, wind protection, and fast drying. If you would like more information about HPMC for putty powder, please contact our MilaCellTM representative.

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