Interior Wall Putty: Dry Climate vs Humid Climate — Two Different Products

Interior putty looks like the simplest product — powder, water, smooth it on. But the same formula that works in northern China fails in the south. The cause is not the recipe. It is the climate.

Quick Answers

1. One Product, Two Climates

There is no single "interior putty" that works everywhere. Interior putty splits into two types by climate:

The dividing line is humidity. Get it wrong and the wall looks fine for a few months, then powders and peels.

2. Dry Climate — Quick-Lime Putty

In dry regions, interior putty uses quick lime (CaO) as the binder, with no cement.

Quick lime reacts with water to form calcium hydroxide, then carbonates into calcium carbonate over time. That gives a hard, smooth, white surface — without the grey colour or the higher cost of white cement.

This is the economical choice for dry rooms. It is white, smooth, and cheap.

3. Humid Climate — White-Cement Putty

South of the Yangtze River, in Southeast Asia, and along tropical coasts, the air is always damp. In these regions, quick-lime putty is the wrong choice.

Why: calcium hydroxide (the hardened form of quick lime) absorbs moisture from the air. Over months, the putty softens, loses strength, and powders or peels off the wall.

In humid regions, switch to a white-cement base:

This is close to exterior putty. White cement holds its strength in damp air. Quartz sand adds dimensional stability. Higher RDP adds water resistance.

4. How to Tell Which Climate You Are In

Do not guess. Check the humidity, not the temperature.

Dry — northern China, inland provinces, Middle East desert, North Africa. Low air humidity, cold or hot but dry.

Humid — south of the Yangtze River, Southeast Asia, coastal tropical areas, near the equator. High air humidity all year.

A simple test: does laundry dry fast indoors, or stay damp? Does metal rust easily? Does the wall "sweat" in spring? If yes, you are in a humid climate — use white-cement putty.

5. The Most Common Mistake

Using quick-lime putty in a humid region.

It is the single most common failure we see. A formulator in a tropical market copies a northern Chinese formula. The putty passes inspection, sells, and six months later customers complain about powdering and peeling walls.

The fix is not more RDP or more HPMC. The fix is changing the binder — quick lime to white cement.

The reverse mistake — using cement putty in a dry region — is less serious. It works, it just costs more and is slightly grey. But the humid-region mistake is fatal.

6. CHARING Products by Climate

7. FAQ

Why does my putty work in the north but powder in the south?

Humidity. Quick-lime putty absorbs moisture from damp air and loses strength. Switch the binder to white cement.

What is the difference between putty and cement putty?

putty uses quick lime (CaO) as the binder — white, smooth, cheap, for dry regions. Cement putty uses white cement — stronger in damp air, for humid regions.

Can I just add more RDP to fix a quick-lime putty in a humid region?

No. More RDP helps water resistance, but it cannot stop the calcium hydroxide from absorbing moisture and losing strength. Change the binder.

How do I know if my market is humid?

Check the air humidity, not temperature. If walls sweat in spring, metal rusts fast, or laundry stays damp indoors — it is humid. Use white-cement putty.

Is white-cement putty more expensive?

Yes, white cement costs more than quick lime. But in a humid region, the quick-lime putty fails, so the "cheaper" option ends up costing more in complaints and rework.

Note: JG/T 298 covers interior putty, JG/T 157 covers exterior. The climate split above applies to interior putty. Always test with your own raw materials and local climate.

For technical inquiries: info@sdcharing.com 

Shandong Charing Industry Co., Ltd. 

www.sdcharing.com