Solutions to the most common problems in exterior paint construction!

There will be various problems in the construction process of exterior wall coatings.

01 Slow dry and stick back

After the paint is brushed, the paint film does not dry for more than the specified time, which is called slow drying

Causes:

1.

2.

3.

4.

5.

Approach:

1.

2.

02 Powdering: the paint film becomes powdery after brushing

Causes:

1.

2.

3.

4.
The paint is mixed with too much water when painting
.

The solution to chalking:

Clean up the powder first, then use a sealing primer with good performance as a primer, and then re-spray imitation stone paint with good weather resistance
.

03 Discoloration and fading

cause:

1.
The humidity in the substrate is too high, and the water-soluble salt crystallizes on the surface of the wall, causing discoloration and fading
.

2.
The inferior imitation stone paint is not made of natural colored sand, and the base material is alkaline, which damages the pigment or resin with weak alkali resistance
.

3.
Bad weather
.

4.
Improper selection of coating materials
.

Solution:

If you see this phenomenon during construction, you can first wipe or shovel off the surface in question, let the cement dry completely, and then apply a layer of sealing primer and choose a good imitation stone paint
.

04 Peeling and flaking

cause:

Due to the high humidity of the base material, the surface treatment is not clean, and the brushing method is incorrect or the use of inferior primer will cause the paint film to detach from the base surface
.

Solution:

In this case, you should first check whether the wall is leaking.
If there is leakage, you should first solve the leakage problem
.
Then, peel off the peeled paint and loose materials, put a durable putty on the faulty surface, and then seal the primer
.

05 Foaming

After the paint film is dry, there will be bubble points of different sizes on the surface, which can be slightly elastic when pressed by hand
.

cause:

1.
The base layer is damp, and the evaporation of water causes the paint film to blister
.

2.
When spraying, there is water vapor in the compressed air, which is mixed with the paint
.

3.
The primer is not completely dry, and the topcoat is applied again when it encounters rain.
When the primer is dry, gas is generated to lift the topcoat
.

Solution:

If the paint film is slightly blistered, it can be smoothed with water sandpaper after the paint film is dry, and then the topcoat is repaired; if the paint film is more serious, the paint film must be removed, and the base layer should be dry.
, and then spray with imitation stone paint
.

06 Layer (also known as bite bottom)

The reason for the layering phenomenon is:

When brushing, the primer is not completely dry, and the thinner of the top coat swells the lower primer, causing the paint film to shrink and peel
.

Solution:

The coating construction must be carried out according to the specified time interval, the coating should not be applied too thickly, and the topcoat should be applied after the primer is completely dry
.

07 Hanging

On construction sites, paint can often be found sagging or dripping from the walls, forming a tear-like or wavy appearance, commonly known as teardrops
.

cause:

1.
The paint film is too thick at one time
.

2.
The dilution ratio is too high
.

3.
Brush directly on the old paint surface that is not sanded
.

Solution:

1.
Apply multiple times, each time with a thin layer
.

2.
Decrease the dilution ratio
.

3.
Sand the old paint surface of the object being brushed with sandpaper
.

08 Wrinkling: The paint film forms undulating wrinkles

cause:

1.
The paint film is too thick and the surface shrinks
.

2.
When the second coat of paint is applied, the first coat is not dry yet
.

3.
The temperature is too high when drying
.

Solution:

To prevent this, avoid applying too thick and brush evenly
.
The interval between two coats of paint must be sufficient, and it is necessary to ensure that the first layer of paint film is completely dry before applying the second coat
.
 

09 Serious cross-contamination exists

cause:

The surface layer did not pay attention to the distribution on the grid during the construction process, resulting in the appearance of rolling off
.

Solution:

In the construction process, every construction step must be followed to avoid the damage of cross-contamination.
At the same time, we can choose auxiliary coatings with anti-aging, anti-high temperature and strong radiation resistance to fill, which can also ensure the reduction of cross-contamination
.

10 There is a lot of smearing unevenness

cause:

The large area of ​​cement mortar results in slow drying time, which will cause cracking and hollowing; MT-217 bentonite is used in imitation stone paint, and the construction is smooth and easy to scrape
.

Solution:

Carry out an average division treatment, and evenly match the mortar during the plastering process of the foundation house
.

11 Whitening in contact with water, poor water resistance

Phenomenon and main reasons:

Some imitation stone paints will turn white after being washed and soaked by rain, and return to their original state after the weather is fine.
This is a direct manifestation of the poor water resistance of imitation stone paints
.

1.
The quality of the emulsion is low

In order to increase the stability of the emulsion, low-grade or low-grade emulsions often add excessive surfactants, which will greatly reduce the water resistance of the emulsion itself
.

2.
The amount of lotion is too low

The price of high-quality emulsion is relatively high.
In order to save costs, manufacturers only add a small amount of emulsion, which makes the imitation stone paint loose and not dense enough after drying.
The water absorption rate of the paint film is relatively large, and the bonding strength is correspondingly reduced.
In rainy weather for a long time, the rainwater will penetrate into the paint film, causing the imitation stone paint to turn white
.

3.
Excessive thickener

When manufacturers make imitation stone paint, they often add a large amount of carboxymethyl cellulose, hydroxyethyl cellulose, etc.
as thickeners.
These substances are water-soluble or hydrophilic, and remain in the coating after the coating is formed into a film.
, greatly reducing the water resistance of the coating
.

Solution:

1.
Choose a high-quality lotion

Manufacturers are required to choose high-molecular acrylic polymers with very good water resistance as film-forming substances to improve the water resistance of imitation stone paint from the source
.

2.
Increase the emulsion ratio

Manufacturers are required to increase the proportion of the emulsion, and do a lot of comparative tests on the addition of the imitation stone paint emulsion to ensure that a dense and complete paint film is obtained after the imitation stone paint is applied to block the invasion of rainwater
.

3.
Adjust the proportion of hydrophilic substances

In order to ensure the stability and workability of the product, it is necessary to add hydrophilic substances such as cellulose.
The key is to find a precise balance point, which requires manufacturers to study the properties of hydrophilic substances such as cellulose through a large number of repeated tests.
Reasonable ratio
.
It not only ensures the effect of the product, but also minimizes the impact on water resistance
.

12 Spray splash, serious waste

Phenomenon and main reasons:

Some imitation stone paints will lose sand or even splash around when spraying.
In severe cases, about 1/3 of the paint can be wasted
.

1.
Improper grading of gravel

The natural crushed stone particles in the imitation stone paint cannot use particles of uniform size, and must be mixed and matched with particles of different sizes
.

2.
Improper construction operation

It may be that the spray gun diameter is too large, the spray gun pressure is not properly selected and other factors can also cause splashing
.

3.
Improper coating consistency

Improper adjustment of paint consistency can also cause sand drop and splash when spraying, which is a serious waste of material
.

Solution:

1.
Adjust gravel grading

Through the observation of the construction site, it is found that excessive use of natural crushed stone with small particle size will make the surface texture of the paint film low; excessive use of crushed stone with large particle size will easily cause splashing and sand loss.
to achieve uniformity
.

2.
Adjust construction operations

If it is the gun, you need to adjust the gun caliber and pressure
.

3.
Adjust paint consistency

If the consistency of the paint is the cause, the consistency will need to be adjusted
.

13 Imitation stone paint flower

Phenomenon and main reasons:

1.
The influence of the pH of the base layer, if the pH is greater than 9, it will lead to the phenomenon of blooming
.

2.
During the construction process, uneven thickness is prone to blooming.
In addition, too little imitation stone paint spraying and too thin paint film will also cause blooming
.

3.
In the production process of imitation stone paint, the proportion of cellulose is too high, which is the direct cause of blooming
.

Solution:

1.
Strictly control the pH of the base layer, and use an alkali-resistant sealing primer for back-sealing treatment to prevent the precipitation of alkaline substances
.

2.
Strictly implement the normal construction amount, do not cut corners, the normal theoretical coating amount of imitation stone paint is about 3.
0-4.
5kg/square meter

3.
Control the cellulose content as a thickener in a reasonable proportion
.

14 Imitation stone paint yellowing

In simple terms, the yellowing of imitation stone paint means that the color turns yellow, which affects the appearance
.

Phenomenon and main reasons:

Manufacturers use poor acrylic emulsions as binders.
The emulsions will decompose when exposed to ultraviolet rays from the sun, precipitating colored substances, and eventually causing yellowing
.

Solution:

Manufacturers are required to choose high-quality emulsions as binders to improve product quality
.

15 The paint film is too soft

Phenomenon and main reasons:

Qualified imitation stone paint film will be very hard and cannot be pulled with fingernails
.
Too soft paint film is mainly due to improper selection of emulsion or low content, resulting in insufficient tightness of the coating when the paint film is formed
.

Solution:

When producing imitation stone paint, manufacturers are required not to choose the same emulsion as the latex paint, but to choose a composite solution with higher cohesion and lower film-forming temperature
.

16 chromatic aberration

Phenomenon and main reasons:

The same batch of paint is not used on the same wall, and there is a color difference between the two batches of paint
.
The color of the imitation stone paint coating is completely determined by the color of the sand and stone.
Due to the geological structure, each batch of colored sand will inevitably have color difference.
Therefore, when entering materials, it is best to use the colored sand processed by the same batch of quarry.
full to reduce chromatic aberration
.
The paint layered or floated on the surface during storage, and the paint was not fully stirred before spraying
.

Solution:

Try to use the same batch of paint for the same wall; put the paint in batches during storage; before spraying, it should be fully stirred before use; when feeding materials, it is best to use the same batch of colored sand processed by quarry, and the whole batch must be imported at one time.

.

17 Uneven coating and obvious stubble

Phenomenon and main reasons:

The same batch of paint is not used; the paint is layered or the surface layer is floating during storage, and the paint is not fully stirred before spraying, and the paint viscosity is different; the air pressure is unstable during spraying; the diameter of the spray gun nozzle changes due to wear or installation errors during spraying ; The mixing ratio is inaccurate, the mixing of materials is uneven; the thickness of the coating is inconsistent; the construction holes are not blocked in time or the post-filling causes obvious stubble; Plan to stubble to form top coat stubble is clearly visible
.

Solution:

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It is required to use paint with anti-ultraviolet, anti-aging and anti-sunlight pigments, and strictly control the addition of water during construction, and do not add water at will to ensure the same color; in order to prevent the pollution of the surface layer, a finish paint should be applied in time 24 hours after the coating is completed.

.
When brushing the finish, be careful to prevent it from running or being too thick to form a flowery feeling
.
During the construction process, the construction should be organized in accordance with the construction procedures to avoid professional cross-contamination or damage during construction
.

21 Yin and Yang angle cracks

Phenomenon and main reasons:

Sometimes cracks appear at the yin and yang corners.
The yin and yang corners are two intersecting surfaces.
During the drying process, there will be two different directions of tension acting on the paint film at the yin and yang corners at the same time, which is easy to crack
.

Solution:

If the yin and yang corners of the cracks are found, use the spray gun to spray again thinly, and spray again every half an hour until the cracks are covered; for the newly sprayed yin and yang corners, be careful not to spray thickly at one time when spraying, and use a thin spray multi-layer method.
, the spray gun should be far away, the movement speed should be fast, and it cannot be sprayed vertically to the yin and yang corners.
It can only be scattered, that is, spray two sides, so that the edge of the fog flower sweeps into the yin and yang corners
.