Water Based Paint Problems&Solutions Pt3 – Bagging, Blistering and Bubbles.

You like eating Aero chocolates? We do to. But bubbles are meant to be kept for chocolates, and should not be on your walls. Here’s what to do if you find bubbles on your walls..

What is Bagging/Blistering?

‘Bagging’ or ‘blistering’ refers to bag shaped blisters on your wall, that are filled with water or other liquid. If they are not intact, they are dried out and perished and flaking. These blisters can range anywhere from 0.5cm to 1m in diameter.

What causes bagging/blistering?

Basically, blistering happens when the top coat of paint parts ways with the coats beneath it. The top coat can even take away multiple underlying coats of paint with it, like a paint stripper. This process is very difficult to predict, and it may happen over the course of a couple of months, or suddenly. Blistering, happens because;

  • Too much moisture, has entered or is entering at the back of the paint film.
  • The masonry structure has not dried – and you have painted on it.
  • the moisture or ‘vapor’ barriers related to the structure, have been designed poorly.
  • An uncleaned wall has been primed or painted on – Presence of oil and grease, like that found on kitchen walls, can prevent the paint from bonding with the surface being painted. (for outside walls exclusively Paint Doctor has a wonderful article on this called ‘Importance of High Pressure Washing’.
  • Painting just before or after it rains. This can be just as dangerous as painting on a wet wall. Humid days can lead to water filled blisters.
  • Using a latex based paint to repaint a surface that is covered in oil based paint. Mixing types of primer and paint on the same wall can lead to problems, especially on exteriors. Heat causes surfaces to expand, and latex and oil paints behave differently in that situation. Ultimately, the latex may take the oil clean off the wall.
  • A suitable primer has not been used. Primers prepare the surface to be painted on, grooming the surface to accept a good and steady bond. Though some paints will bond to surfaces without a primer, good primers can prevent bubbles from forming if the paint being used is not compatible with the surface.
  • Painting when it’s too hot – above 27 C. In hot weather, the upper stratum of paint may dries quickly, which traps and vaporizes the paint’s solvents. The solvents in turn create bubbles.

Although blistering can occur with just about any kind of fresh paint finish, latex and acrylic paints are often more prone to this problem. They can happen on interior or exterior surfaces, and they’re more likely to arise when preventive measures haven’t been taken.

How to Remove Bagging/blistering

So, although you’ll need new materials to remove the bubbles, you’ll need entirely the same ones you used before to repaint the surface – this is a ‘duh’ moment. To get started, you’ll need a putty knife or paint scraper, sandpaper, cleaner, a couple rags, joint compound and primer.

Then you charge right at it:

  1. Use the paint scraper or putty knife to scrape the paint bubbles off the wall.
  2. Sand down the area where the bubbles used to be until the area is smooth and the division between the paint and the wall is seamless.
  3. Clean the area that you scraped and sanded, removing any grease or dust from the wall.
  4. Use a joint compound to fill in any pits in the wall.
  5. Sand the joint compound to make the surface smooth.
  6. Re-clean after sanding to ensure that dust from the sanding is wiped away.
  7. Prime area that was just scraped and sanded. Wait for the primer to dry.
  8. Paint the area that was just primed.
  9. Wait for the paint to dry, then apply a second coat.

 

Remember, all of this means nothing if you do not locate the point of moisture ingress, and rectify it. If you cannot rectify the moisture source, a high quality PVC topcoat may have to be applied.

Bagging/blistering preventions?

You’ve heard the old age that ‘prevention is better than cure?’ Prevention of paint bubbles requires proper surface preparation before beginning to paint, though there are a few other tricks and tips that may contribute to the cause..

    • Do not apply paint over a damp or wet surface.
    • Do not paint 4 hours before or after heavy rain – though this is a soft rule and most experienced paint companies will agree that it is very rare to see a rain heavy enough to lift your paint in the 4 hour after period.

  • Don’t paint when the temperature is above 28 C. And paint in the shade whenever possible.
  • If the surface area you you’re painting on is covered in oil based paint. Use another oil based to repaint it.
  • Do not prime or paint an uncleaned wall. Clean, the surface using whatever means necessary. Whether it be a duster, grease remover or household cleaner. Finish it off by drying it with a towel and letting it dry a little longer before moving forward.
  • Prime the surface before painting. Primer will ensure that the bond between your paint and the surface being painted is strong and secure.
  • Consider a conditioner to help keep freshly applied paint from dying too quickly. Water-based paints are compatible with Floetrol, while Penitrol works with oil paints. These are paint extenders that help improve the paint flow for brush and roller work. Avoid using mineral spirits or water for this purpose; excessively thinned paint only compounds the problem.

So, there you have it, we’ll let you get back to eating your Aero chocolate, and watching your movie.

 

 

 

 

 

 

 

 

Water Based Paint Problems and Solutions Pt 2 Snail Trails & Touch Ups

This week, we carry on with specific paint problems that are particular to the south african climate. In this article we will teach you how to remedy badly done touch up jobs, and snail trails

Touch Ups..

Description

Areas of different colour with signs of application directionality and or texture

Causes..

  • A poorly colour matched paint was used.
  • The touch-up coat was applied at different temperature – this can cause it to be lighter or darker than your last finish coat
  • Sun exposure may have caused the applied paint to fade slightly.
  • the original retained paint was used , while the existing in-situ coating has faded.
  • The touch up paint was stored for a prolonged period of time and has degraded or colour developed.
  • Failure to reduce the touch-up paint by up to 25%.
  • Touching up marks that could be removed by washing with a sponge and liquid detergent.
  • The touch-up coat was applied to a porous surface – porous surfaces give problems especially with high-sheen eggshells and higher gloss finishes because unprimed porous substrates absorb more of the paint they leave less of a sheen or gloss.
  • A different type or batch of paint was used – different paint types require different amounts of time to finish. the amount of time between the application of your finish coat and touch-up can affect how well these two coats blend together.
  • An application technique different to the original one was used from the e.g. Touching up with a brush when the original coat was applied by roller.

Preventions and Remedies

How to prevent touch up problems                                       

Prevention, is always better than cure as they say..

So here are 5 easy tips to prevent future touch up problems..

  • Always use the same batch number when available
  • Try to wash the mark off first with a sponge and liquid detergent.
  • Use only enough paint to cover the mark, excess paint may cause a halo.
  • Use a feathering-in technique, avoid dabbing.
  • Thin paint up to 25%.

How to remedy touch up problems

Fortunately, the cure (in this case) is much simpler than the sickness. All you have to do is match your colour coating to the existing colour, and then recoat the entire area from edge to edge/ corner to corner. Priming is essential for better adhesion, sheen uniformity, mildew control and durability. Select a top quality interior paint in the color and sheen of your choice.

 

 

Snail Trail

Description

Snail trails are shiny vertical run-marks seen on dry paint films, they are predominantly seen on matt coatings but can also be seen with some sheen coatings. Streaks generally start to emanate from flat topped walls or parapet walls. They are usually randomly spaced and follow gravitational direction. Although snail trails look like dirt streaks, they are not the same.

Causes

Snail trails happen when the water soluble paint components have been washed away by water. Dry paint films are made up of pigment and binder, but to present the paint in a usable form, many additives are used in the formulation.These additives are mostly water-soluble and remain in the dry paint film until they are effectively washed out by water – be it via rain, dew or by irrigation sprinklers. If the amount of water falling on the surface is low, then only part of the water-solubles are washed out, and they can dry on the surface. This leaves what we call snail-trails. They tend to be sticky, and can act as a dirt trap. This could have occurred within the first 2 – 24 hours depending on the  humidity and dampness experienced during the time of painting, or in rooms of high humidity eg kitchens, bathrooms and showers etc

Preventions and Remedies

  • Avoid painting in adverse weather conditions. eg late afternoon if cool damp conditions are expected in the evening or overnight.
  • If the problem occurs in the first day or two it can usually be rinsed off rather easily, with a damp cloth, soap and water. Problem may occur once or twice again before leachable material is completely removed. When paint is applied in a bathroom, it is helpful to have it dry thoroughly before using the shower. Remove all staining before repainting.
  • Fortunately, more difficult trails weather away within the first 3-6 months or are washed from the film after 2-3 rains. Snail trailing should not affect the ultimate durability of the coating.
  • If none of the above works, recoat taking care to consider touch-up batch variation, difference in application technique etc.