When making and applying putty powder, we will encounter various problems. Today, what we are talking about is that when the putty powder is mixed with water, the more you stir, the thinner the putty will become, and the phenomenon of water separation will be serious.
The root cause of this problem is that the hydroxypropyl methylcellulose added in the putty powder is not suitable. Let’s take a look at the working principle and how we can solve it.
The principle of the putty powder getting thinner and thinner:
1. The viscosity of hydroxypropyl methylcellulose is improperly selected, the viscosity is too low, and the suspension effect is insufficient. At this time, severe water separation will occur, and the uniform suspension effect will not be reflected;
2. Add water-retaining agent to putty powder, which has a good water-retaining effect. When the putty dissolves with water, it will lock a large amount of water. At this time, a lot of water is flocculated into water clusters. With stirring a lot of water is separated, so a common problem is that the more you stir, the thinner it becomes. Many people have encountered this problem, you can properly reduce the amount of added cellulose or reduce the added water;
3. It also has a certain relationship with the structure of hydroxypropyl methylcellulose and has thixotropy. Therefore, after adding cellulose, the entire coating has a certain thixotropy. When the putty is stirred quickly, its overall structure will disperse and become thinner and thinner, but when it is left still, it will slowly recover.
Solution: When using putty powder, usually add water and stir to make it reach the appropriate level, but when adding water, you will find that the more water is added, the thinner it becomes. What is the reason for this?
1. Cellulose is used as a thickener and water-retaining agent in putty powder, but due to the thixotropy of cellulose itself, the addition of cellulose in putty powder also leads to thixotropy after adding water to the putty;
2. This thixotropy is caused by the destruction of the loosely combined structure of the components in the putty powder. This structure is produced at rest and dismantled under stress, that is to say, the viscosity decreases under stirring, and the viscosity at rest Recovery, so there will be a phenomenon that the putty powder becomes thinner as it is added with water;
3. In addition, when the putty powder is in use, it dries too quickly because the excessive addition of ash calcium powder is related to the dryness of the wall, and the peeling and rolling of the putty powder is related to the water retention rate;
4. Therefore, in order to avoid unnecessary situations, we must pay attention to these problems when using it.
When we use putty powder, we always encounter all kinds of strange problems. Of course, it doesn’t matter. As long as we know the principle and the solution, we can prevent such things from happening.
Post time: May-20-2023