QUALITY ISSUE: PAINT PEEL-OFF

January 6, 2017
MABUHAY!

The most common quality issue or punch list in construction during architectural finishing works is PAINT PEEL-OFF in a concrete masonry wall. This quality issue manifest in many forms:

INTERIOR PEEL-OFF

Interior paint peeling off

Skim coat flaking off

CLICK the LINK to READ the related article: Quality Issue: Concrete Hairline Cracks

EXTERIOR PEEL-OFF

PAINT BUBBLES

CLICK the LINK to READ the related article: Concrete Demolition: A Systematic Way of Knocking Down Concrete

PAINT CRACKS

CLICK the LINK to READ the related article: Work Inter-Phase: Why Proper Coordination is Very Critical in Construction

PAINT BLISTER DUE WATER SEEPAGE

PAINT DISCOLORATION

ROOT CAUSE
Incorrect surface preparation

• Application of masonry putty first to the concrete substrate without primer paint.
• Application of powder-based skim coat or gypsum board putty to correct the wavy surfaces of concrete. Most acrylic based paints and all solvent based paints are not compatible with powder base skim coat. Make sure to use acrylic-based skim coat recommended by the paint manufacturer

Insufficient curing time of concrete surface

• The ideal curing period for concrete is 14 -28 days. Since the Philippines is a tropical country, concrete cure fast due to the intense heat of the sun. I also recommend doing the moisture test for concrete at 14 days. Cut a 1ft x 1ft polyethylene sheet and tape it with duct tape or masking tape on the concrete surface. Observe if there still a manifestation of water droplets, then the concrete is not yet fully cured.
• The concrete surface if not yet cured has high alkalinity expressed in pH reading. Alkaline reacts on paint film causing discoloration and overall deterioration. A fresh concrete surface has 13 to 14 pH reading while 14 days concrete has 7 to 8 pH reading which is very ideal for painting works.

Water seepage

• Water seepage is caused by temperature cracks on concrete surfaces which enable the rainwater or moisture from the exterior side to penetrate on paint coated surfaces causing it to bulge or blister.

Wrong Paint

• Painting the wrong kind of paint will eventually result in paint peel off. Paint for metal or wood is not compatible with concrete surfaces.

PAINT PEEL-OFF ADHESION TEST

This destructive test is being conducted to check whether the paint or the base coat adhere to the concrete surface. If the paint coat detached in the base coat, repainting is only recommended. If the base coat detached on the concrete surface, stripping of paint up to bare concrete is recommended.

PAINTING RECTIFICATION METHOD

Surface Preparation 

• Spot scrapping down to bare concrete to remove all paint cracks, paint bubbles. loose and damage paint.
•  For concrete surfaces with cracks, widen the crack by making a 2 to 3mm V-groove. Patch the groove with a mixture of cement and concrete epoxy. For cracks with water leaks, patch the groove with a mixture of cement and water plug.
• For surfaces with a powder, base skim coat, strip to bare the affected area using a grinder.

Primer

• Apply 1 (one) full coat of primer paint as a base coat.

Putty/Skimcoat

• For correction of uneven and wavy surfaces, spot apply the paint manufacturer's recommended masonry putty or acrylic-based skim coat.

Undercoat

• Apply 1 (one) full coat of primer paint as an undercoat.

Top Coat

• Apply 2 coats of specified paint as a final coat.

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