Cracks In New Paint On Pebbledash ?

[WhiteVanJack]

Hi,

I have just painted a pebbledash wall and after drying the paint has developed small cracks in the surface. My 1st thoughts are that the paint has been applied too thickly and when drying out had developed the cracks. However, I would be grateful for any advice on the subject as it is the 1st time I have attempted to paint pebbledash. The wall is due a final coat so hopefully I can "paint over the cracks" when applying the final coat.

The paint is Dulux Trade Weathershield Smooth Masonry Paint and was diluted 1 part water to 5 parts paint for the 1st coat on the unpainted pebbledash then 1 part water to 10 parts paint on the 2nd coat. The 3rd coat is yet to be applied. The paint was applied with a brush.

The same effect also occurred on some historically painted pebbledash, ie, the application of the Dulux paint diluted 1 part water to 10 parts paint when painted over the historic paint (6 years old) gave the same cracking effect when drying.

I have only noticed the effect today a couple of days after applying the previous coats so I have painted a couple of test areas with different dilutions to see if I can resolve the issue. However, any advice most appreciated.

I have uploaded an image below showing the cracks in the paint surface, to get better visibility, please click the image to enlarge it. From a distance of a few yards, the effect is not noticable, however,from close up (1ft) it becomes apparent.

Untitled

• WhiteVanJack
• 16 Oct 2010
• 1

Rgds
Jack

 

[roughcaster]

Maybe another coat will cover them Jack. As you say, it's not much, but you'll want it to look as perfect as possible.

 

[TheDec]

At this moment of time I will not ask you what you mean by a historic paint, looking at your pic the areas subject to breakdown seem to be caused by efflorescence. This is often associated with the entrampment of moisture, where the substrate beneath is no longer allowed to breathe.

The importance here is to establish the age of your property and whether it be of brick or stone build, and also if the interior is lath and plaster or render and skim.

I apologise for the long winded approach, applying the correct sealer in order to cure such as effloresence on exterior paintwork can often have a far more dramatic effect with accord to it's appearance within the interior of the walls.

Dec.

 

[WhiteVanJack]

Thanks for the replies.

TheDec,
To address your points, the property is approximately 100 years old and is brick built. The historic paint I was referring to are the previous coats of paint that had been applied to some of the the pebbledash at the front and rear of the property years ago. The side of the property was unpainted pebbledash until painted last week. The front and rear of the property were previously painted pebbledash and also repainted last week. I am not sure if the inside is lath & plaster or render & skim.

The picture I posted of the cracking paint was taken a couple of days after last weeks painting, ie, picture taken on Saturday after painting the front, rear and side earlier in the week. The previously painted pebbledash at the front and rear of the property did not have the cracked surface, the artefacts on the current finish have only arisen since last weeks painting has dried and are present on all elevations of the property.


roughcaster,
I marked out a couple of test squares on the cracked finish with masking tape them painted over them with different dilutions of the paint (1:10 and 1:5, water to paint) and brushed it so that there were no excess puddles of paint residing between the nooks and crannies and with both dilutions it partially cured the problem. After drying it has possibly removed 65% to 70% of the cracks and it has had 4 days to dry out so it looks hopeful.

However, I think that perhaps it might be prudent to try to fully ascertain the cause of the cracking before embarking on a repaint to try to get rid of the artefacts. I located a similar problem that was posted on the forum approximately 16 months ago and replied bringing it back to the top of the topics list. In that case, the OP resolved the issue by repainting but I would prefer to know how his paintwork is now some 16 months later before I embark on a repaint.


Rgds
Jack

 

[roughcaster]

Good thinking Jack,,,, i hope it works out for ya.

 

[TheDec]

Jack.

I can understand your frustration here and I will try my very best to help you solve your problem. Viewing the cracks that have appeared in your new paintwork bear a distinct resemblance to efflorescence.

Many of the causes with regard to the nature of efflorescence remain a mystery, however it is often associated with salts that are contained within masonry.

I need here to ask you a few questions, was the wall in question wet when you painted it, the historic paint of which you say was applied years ago, was this perhaps chalky in appearance if perhaps you run your hand over it would you have had a powdery residue on it.

I have good reasons for asking you these things, so bear with me and I will try my best for you.

One more thing, are these areas just random.

Dec.

 

[WhiteVanJack]

TheDec,

Thank you for your reply.

The 3 walls in question were dry when painted, we had not had rain of any note prior to painting and the walls were dry to the touch. The previously painted areas did not seem to have a powdery residue on the surface as I hope I would have noticed this when brushing them down prior to painting. Several days before painting commenced I took a relatively soft brush and brushed down all of the walls to remove any dirt and dust from all 3 walls and any loose pebbles from the unpainted wall. If there had been any efflorescence then I am reasonably sure that I would have noticed it at this time.

I think I can see where you are going with the efflorescence idea and actually the picture I uploaded does have a resemblance to it. My understanding of efflorescence is that it is the external crystallisation of dissolved mineral salts that have been transported in solution via rising or penetrating damp which manifests itself as a chalky deposit on the exterior. The areas are not just random, they are all over all 3 elevations including the gable end apex which is nearly 30 feet above the ground.

In the other topic on the subject, the OP uploaded a picture which is probably a better illustration of the artefact than the one I uploaded. I hope it is OK if I add the picture from the other topic below. If it is not would an admin or the OP please let me know and I will remove the picture.

Untitled

• WhiteVanJack
• 21 Oct 2010
• 1

Rgds
Jack

 

[joe-90]

Your problem is in your head Jack. Just paint it and stop banging on about problems that don't exist.

 

[WhiteVanJack]

Your problem is in your head Jack. Just paint it and stop banging on about problems that don't exist.

Lost your specs today joe or are your peepers governed by your amoebic pea brain not working. If your dysfunctional peepers were working you would be able to read that I have painted the wall FFS. Now, be a good little boy and run home, yer mammy has bought milky bars for you to get all excited about....

 

[joe-90]

Last week you were panicking about your outside wall getting wet in the rain. Get help mate.

 

[WhiteVanJack]

Last week you were panicking about your outside wall getting wet in the rain. Get help mate.

joke-90,

That was over 4 weeks ago, the section of wall that was wet due to the guttering been removed has dried out and was painted after drying out. Your brain is becoming void of nutrition, get home and scoff them milky bars, nothing for you here, move on, thats a good little boy.

 

[johnheritage]

Yeah, one reason for that kind of cracking is that the surface was damp before the paint went on.

Another is that the paint has been applied to heavily.

I would recommend you leave that alone for a few weeks and hope for some good weather prior to repainting it, so it has a chance to dry fully if it's just trapped moisture.

When repainting, consider just going over the cracks first to check it's not going to do it again, and use the least amount of paint needed to cover it. Don't cake them.

 

[WhiteVanJack]

johnheritage,

Thanks for the reply.

I propose to wait another 2 weeks then possibly give it another coat. I marked out and painted some test squares in consideration of a repaint and the test squares are OK after 1 week. That should give me over 3 weeks since it was last painted before the next session

The reason that I am personally leaning towards the paint being originally applied too heavily is that the artefact is present all over the building rather than specific areas and we had good weather for the week or so before the painting.

I have not ruled out the fact that it could have been damp or efflorescence so that is why I think a few weeks delay might allow me to get a more balanced view rather than rushing into a quick fix.


Rgds
Jack

 

[TheDec]

Jack.

You are wise to take that approach, yet after looking at both pics I am of the opinion that it is not efflorescence and after reading your well explained reply neither does it seem to be any form of contamination carried from your already painted wall.

Therefore it does seem to be a to thickly applied coating which has caused your problem, yet I had to ask.

I hope all turns out well for you.

Good luck

Dec.

 

[joe-90]

It's just shrinkage cracking. Thin your paint a bit.