Achieving a flawless execution in waterproof coating projects is
far from being as simple as it seems. It's not just about applying
the coating; every step is crucial. Besides selecting high-quality
waterproof coatings, understanding the properties of these
coatings, adhering to proper techniques, and paying close attention
to every detail are essential to ensure a leak-proof outcome. Only
through meticulous execution can the waterproofing be done right,
ensuring absolute water tightness.
Sagging on Vertical Surfaces
- Definition: Sagging refers to the presence of streaks or cracks on the
coating surface after application, commonly seen in JS waterproof
coatings on vertical surfaces.
- Cause: Applying the coating too thickly in one go or concentrating the
application in a small area.
- Solution: For vertical applications, it's recommended to apply at least
three coats to achieve a thickness of 1.5mm. Ensure the roller
moves in varied directions to evenly spread the coating, applying
vertically then horizontally to avoid sagging.
Coating Peeling from the Base
- Definition: This occurs when the coating easily peels off from the base,
especially in large pieces, posing significant risks, particularly
on vertical surfaces. This issue is most common during summer.
- Cause: Causes include a loose or dusty base, or the surface strength of
the base being lower than the adhesion strength between the coating
and the base, coupled with inadequate base wetting or priming
before application.
- Solution: Apply a base treatment agent or dilute the waterproof coating for
priming. This improves the surface strength of the base and the
adhesion between the coating and the base. Priming significantly
increases adhesion and full-bond rate between the coating and the
base.
Cracking at Flat Surfaces and Inside Corners
- Definition: Cracks on flat surfaces appear as crazing, linear, or triangular
openings, while inside corners usually show as long, straight lines
over a large area, primarily occurring in cement-based waterproof
coatings.
- Cause: Causes for flat surface cracking include a loose base or
excessive dust, leading to adhesion failure and shrinkage cracks
during curing. Corner cracking mainly occurs when corners are not
rounded off, resulting in uneven drying and shrinkage.
- Solution: Clean the base thoroughly before application. Repair loose areas
with mortar or leak-stop products. Keep the base moist but not wet,
and consider priming to prevent bubbles, pinholes, and cracks.
Round off inside corners to a radius of >5cm and apply a thinner
layer at these points.
Pinholes and Blistering
- Definition: Numerous small holes appear after application, with some areas
blistering. This is common in cement-based waterproof coatings and
can extend to all types of coatings.
- Cause: When concrete or the base absorbs water, air trapped inside rises
to the surface, forming bubbles. If these bubbles burst after
coating application, pinholes result; if not, blistering occurs.
- Solution: Saturate the base with water before application. Dilute materials
like JS or acrylic coatings for a base layer to seal pores. For
K11/mortar products, saturating the base is most effective.
Applying a base treatment agent can also address this issue.
Sand Loss and Powdering
- Definition: After curing, touching the material surface causes sand to fall
or leaves dust on the hand, indicating low surface strength. This
is often seen in K11/mortar products and cement-based crystalline
waterproof coatings.
- Cause: Usually due to incorrect water-to-cement ratio or the material
being washed by water before curing.
- Solution: Follow packaging instructions for two-component mortars; water
addition should not exceed 20% of the liquid component. For
single-component mortars, a water-to-mortar ratio of 21~23:100 is
appropriate; for cement-based crystalline waterproof coatings, a
water-to-crystalline ratio of 0.3:1 is recommended, with some
flexibility within manufacturer guidelines.
Settlement After Mixing
- Definition: Two-component materials or single-component mortars show
separation after mixing, with a milky liquid on top and sediment at
the bottom.
- Cause: Often due to incorrect water-to-cement ratio, with excessive
water exceeding the emulsion's carrying limit, disrupting the
material's stability.
- Solution: Adhere strictly to mixing ratios. For two-component mortars,
adding up to 20% water of the liquid component is acceptable for
ease of application; for single-component mortars, a
water-to-mortar ratio of 21~23:100 is suitable; for cement-based
crystalline waterproof coatings, a water-to-crystalline ratio of
0.3:1 is advised, within the limits set by the manufacturer.
Delayed Curing
- Definition: The material does not cure for an extended period (a week or
more), or the surface dries but blisters or wrinkles appear during
water tightness tests, commonly occurring with acrylic waterproof
coatings.
- Cause: Acrylic waterproof coatings cure by water evaporation. In closed,
humid spaces with poor air circulation, curing may be significantly
delayed.
- Solution: Avoid using acrylic waterproof coatings in closed or humid
spaces. If already applied, enhance air circulation and raise the
ambient temperature to promote curing. If uncured material causes
issues in water tightness tests, remove the entire waterproof layer
and apply a two-component coating.
Feiyang has been specializing in the production of raw materials
for polyaspartic coatings for 30 years and can provide polyaspartic
resins, hardeners and coating formulations. Some of our
polyaspartic coating formulations: Polyaspartic Coating
Feel free to contact us: marketing@feiyang.com.cn
Our products list:
Learn more polyaspartic knowledge: Polyaspartic FAQ
