Micro-blistering

[Phil Speight]

This has been discussed before but I think it is worth re-visiting. When a boat we have painted or, more particularly , when one painted by someone else with our paint starts to develop pin head size blisters our customers complain to us. Quite understandable and to be expected. What we don`t get is people ringing us to complain when somebody else`s paint does the same , however I know of a number of cases where the problem has occured when other manufacturer`s products have been used - I just don`t get to hear about the majority them. I do know though that for an unfathomable reason in the period between last summer and now it`s happened a lot.

Micro-blistering is a well known problem, nothing new at all, and is usually caused by moisture trapped in the primer at the bottom of a paintjob. Brushing synthetic primers are particularly vulnerable because they are designed to be absorbent - that`s how they work. This can be obvious , like when a primed sailaway is left out in the weather, or it can equally be caused by damp, high humidity or condensation. These can be undiscernable to the painter. This not withstanding we have, for our own sake as much as for anyone else`s, done exhaustive checks and tests both here and at the factory to be make absolutely sure that nothing has changed in our formulations and ingredients. Nothing has.

So; beware. If there is moisture in the air or a danger of condensation forming late in the day, or whatever, there is a risk while a boat is standing in primer. The fact that it is also standing in cold water hardly helps. It is a good idea, if a dock is heated, to keep the place at an even temperature all the time - in other words leave the heating on when you leave in the evening. If there is no heating be particularly mindful of temperature changes which can cause anything from blooming of the paint to massive condensation. If you have conditions that are liable to any of the above there are a couple of things you can do to lessen the risks. Put around 10% of gloss paint in your primer and , while it is still tacky apply a full gloss coat. You will then have to rub down before applying any undercoat. These precautions will help.

I`m writing this in the certain knowledge that it is a general problem with the old-fashioned "traditional" paint systems most of us use on the canal, whoever`s paint you use, and that the canal itself, by it`s nature, is part of the problem. We have no such issues in any other market and ,as I have said , it has never previously been too much of an issue even on boats unless it has been provoked by moisture trapped under rubber mats, flower troughs, coiled ropes and the like. For some reason though there has been a lot of it recently. Maybe the average amount of moisture in the atmosphere has been unusually high or something, or our weather really is changing. On top of that ( literally I guess ) ice under frozen snow could well prove to be as effective a barrier to the evaporation of trapped moisture as a rubber mat. I`m told that steel itself can harbour moisture. " Holding" primers generally are only partially effective.

More modern two pack spray primers are the answer if you have the facilities to apply them but not many canalside painters have. In the longer term we are now trialling an additive for old fashioned solvent based one pack brushing primer. It will make such products much more water resistant. It hasn`t been done before because it will effectively make the product into a two pack and we need it to brush well ( which will have to be the really clever bit ), it will require a change of method on the part of the painter ( an extra rub down ) and it will be expensive. We still have to establish also whether or not it would create adhesion problems with the subsequent layers of paint. In the meantime try the tricks I have mentioned above - they are a worthwhile precaution in difficult conditions - and it`s always possible that we are stuck with them for years to come. I`d prefer to think not because I`m still a petrolhead.

I hope this doesn`t get me one of those newsgroup arguments - I really am trying to be helpful despite the "Mr.Grumpy" epithet I seem to have earned myself.

Phil

[Grace and Favour]

Very informative Phil - - - and thank you for taking the time to explain . .

 

Like so many peeps - I joined this forum to learn about the broadest aspects of boating before I leap in and buy one . . and your advice has certainly contributed to that information base.

[dor]

I have been a victim of micro-blistering, and despite having my boat repainted in a heated shed am suffering from it again. I know of several boats painted in the last years or so that are suffering from it.

 

I just wonder if it is the result of changes to paint formulations to try and reduce the VOC content. Perhaps the paints are ok in ideal situations, but are more susceptible to the causes of micro-blistering which I understand can result from solvent content of the paint as well as moisture.

[Nickhlx]

On a boat that was new /painted last spring, ( in a heated tent for a few weeks) would it be expected that the the paintwork be under some sort of warranty if it suffered some micro-blistering, e.g sides OK and roof blistered, or what would be the expected warranty period of a new boat on paint ?

 

Nick

Edited January 26, 2010 by Nickhlx

[Tony Brooks]

Thanks Phil,

 

What I do not understand is the number of painters who seem to use those big blower heaters burning diesel or paraffin in their docks. I would have thought that was just asking for condensation problems.

 

I suspect that is why our paint microblisterd and the tail that there had been sabotage at the paint factory may have just have been an excuse.

[bag 'o' bones]

micro blistering - a problem that can be solved with the use of infra red heaters.

[kitman]

Thanks Phil,

 

What I do not understand is the number of painters who seem to use those big blower heaters burning diesel or paraffin in their docks. I would have thought that was just asking for condensation problems.

You're right. Also if the diesel heaters spit unburnt fuel over the side of the boat and its not cleaned up, you end up with craters down the side of the boat.

 

As to the reasons why they painters them, it's probably because it's what they are given to use. Dont forget not all painters are self employed, some work for boatyard owners. The boatyard owners I've worked for in the past have tended to dismiss my advice on painting, maybe because they dont understand the reasoning behind it.

 

Like one I remember who used to come round and turn off the infa red heaters after we'd gone home, saying that we were wasting electricity and he couldnt afford it (Fair enough). We explained why we'd left them on (Condensation, this was in January) and it was dismissed as an excuse because we had 'forgotten to turn them off'. Of course the paintwork micro blistered soon after the job was finished.

 

From my basic understanding the reason for this particular micro blistering goes like this: There was a high Relative Humidity in the dock caused by the time of year, and absence of heat. The steel temperature dropped sufficiently below the ambient temperature for a dew to form. Water was absorbed into the paint surface. Water was trapped in the paintwork underneath subsequent coats of paint. Water tried to escape forming blisters

 

It's a typical example I surpose

 

Just like to add, I am working for myself now, I have electric heaters (Dry Heat) and temperatures are maintained! (And the boatyard owner was right, it does coat a fortune!!)

[Postcode]

Phil,

 

This is a really positive post from someone who is experiencing the modern 'it must be someones fault' attitude. I guess the many happy purchasers of your products can testify its not the paint. Hopefully those that do experience problems with pain (from whoever) work with the manufacturer to understand the problem.

[Naughty Cal]

Another good tip is that covering boats with covers that are none breathable also brings on the onset of blistering paintwork. As can leaving items lying around on the paintwork for long periods, they hold the damp against the paintwork and with no ventilation the damp stays put.

[Phil Speight]

The point about infra-red heaters is a very good one as is the one about paraffin. The "sabotage at the paint factory" sounds like utter bollocks. I have a paint technician from the fatory with me as I write this and his view of the suggestion was , where printable , on the lines of " Yeah - we send paint out with micro-blistering built in ! "

I should have made clear that the problem we are chasing seems only to afflict new-builds, boats that have stood in primer and repaints done from bare metal and the boats that do have a problem are an insignificant number compared with those that don`t - unless it`s a) your boat , your paint or c) - you painted it.

Phil

 

On a boat that was new /painted last spring, ( in a heated tent for a few weeks) would it be expected that the the paintwork be under some sort of warranty if it suffered some micro-blistering, e.g sides OK and roof blistered, or what would be the expected warranty period of a new boat on paint ?

 

Nick

We always accept responsibility for problems that occur in any paintwork we do and most of the professionals I know well do the same. "Fault" and "responsibility" aren`t always the same thing!

 

I have been a victim of micro-blistering, and despite having my boat repainted in a heated shed am suffering from it again. I know of several boats painted in the last years or so that are suffering from it.

 

I just wonder if it is the result of changes to paint formulations to try and reduce the VOC content. Perhaps the paints are ok in ideal situations, but are more susceptible to the causes of micro-blistering which I understand can result from solvent content of the paint as well as moisture.

You`re right - solvent entrapment can also cause micro-blistering, usually when paint has skinned over too quickly because of too high a temperature or too high a build. However , of the boats we have studied ( and we`re looking at a couple today ) the problem is moisture - not solvent. Apart from that - reduced VOC`s would reduce the likelyhood of solvent entrapment not increase it.

Edited January 27, 2010 by Phil Speight

[Nickhlx]

We always accept responsibility for problems that occur in any paintwork we do and most of the professionals I know well do the same. "Fault" and "responsibility" aren`t always the same thing!

 

 

Thanks Phil,

 

Nick

[Ally]

A lot of useful thoughts Phil!

 

For what it's worth, I have seen this problem happen with other paints, such as Epifanes paints as just one example,.....so it's surely NOT just a problem Craftmaster are experiencing. This leads to the thinking that it really can't be the actual paint that is a problem. The last year does indeed seem to have brought about a 'rash' of this problem, and is thus causing much heart ache for all involved.....owners/painters/builders/suppliers are all suffering, and it seems hard to pin point the exact problem. Perhaps because we have been dealing with hugely changing temperatures and extremes of high and low temperatures over the year.

 

I shall be following this thread with interest!

[RLWP]

I'm thinking on my feet here, so it may all be rubbish

 

Is there some way to analyse the blisters? Presumably whatever caused them is trapped under the top coat of paint. So, if pierced with a pin, is there anything in them, could it be detected? Can they be dissected to see which layers have separated from what?

 

Richard

 

I think I'm inventing paint forensic science...

[Tony Brooks]

I'm thinking on my feet here, so it may all be rubbish

 

Is there some way to analyse the blisters? Presumably whatever caused them is trapped under the top coat of paint. So, if pierced with a pin, is there anything in them, could it be detected? Can they be dissected to see which layers have separated from what?

 

Richard

 

I think I'm inventing paint forensic science...

 

 

When mine micro-blistered I paid to have some paint flakes I removed analysed and reported upon. Mainly because I suspected an attempt would be made to get me to pay more money to put it right.

 

The report mentioned signs of rust under the blisters with good adhesion between coats.

 

Just to clarify the sabotage thing I mentioned in my earlier post. The company concerned had just been taken over by an international player (no, not that one directly - I did not use an uppercase I) and I hear massive redundancies were in the air.

[Phil Speight]

I'm thinking on my feet here, so it may all be rubbish

 

Is there some way to analyse the blisters? Presumably whatever caused them is trapped under the top coat of paint. So, if pierced with a pin, is there anything in them, could it be detected? Can they be dissected to see which layers have separated from what?

 

Richard

 

I think I'm inventing paint forensic science...

There`s only going to be one of two things under the blisters ( unless it is another problem entirely ) - water or solvent. The one smells, the other doesn`t. "Paint forensics" already exist. I spent the last one and a half days looking at blisters , at the liquid in the blisters and what surface was exposed under the blisters. The factory have paint samples , swabs of liquid, test panels and lord knows what else.The micro-blistering we are concerned with ( and I now have absolute evidence of the same problem afflicting paint from three other respectable manufacturer/suppliers ) is being caused by moisture - that is water. I know at least one famous manufacturer whose response to the painters in question has been " Theres`s nothing wrong with the paint - we`ll let you have some more at a reduced price but we are not responsible for the problem." I think they are entirely correct - but we at least are trying to find out why the problem is happening so often - for everyone`s sake.

Here`s an example of a boat we saw yesterday. A cabin side fairly consistently micro-blistered turns a corner ( without a break in the painting operation ) becomes the back bulkhead and is perfect. It stays perfect down the other side. Same paint, same brush , same painter , same dock, same time .

 

What we are finding paintwise under the blisters is usually primer , sometimes bare metal, very occasionaly undercoat .

The problem seems TO ME ( the chemists still have their heads together ) to be temperature/humidity/moisture affecting and then coming from either the steel or the primer. It surfaces after a variable length of time because the impermeable top coats have sealed it in. One thing is for sure with our paint system and all the others I know are having problems - there is NO water in the paint , undercoat or primer when it leaves the factories.

 

I`ll keep you up to date on this whole issue because I know some of you meed answers and some of you are just generally interested. I also know that people are blaming various paints for the problem and I know that the answer lies elsewhere.

Edited January 28, 2010 by Phil Speight

[churchward]

You`re right - solvent entrapment can also cause micro-blistering, usually when paint has skinned over too quickly because of too high a temperature or too high a build. However , of the boats we have studied ( and we`re looking at a couple today ) the problem is moisture - not solvent. Apart from that - reduced VOC`s would reduce the likelyhood of solvent entrapment not increase it.

 

In my limited experience of spraying cars using cellulose paint and thinners ( I know enamel is a different beast of course) solvent entrapment rather than moisture can cause a different effect. More like micro pin holes in the paint where the solvent has made its way to the surface and escaped. So you get many small indentations in the paint about the size of a pin-prick rather than a small bubble of paint as with moisture entrapment.

[Grace and Favour]

There`s only going to be one of two things under the blisters ( unless it is another problem entirely ) - water or solvent. . . . . . .

 

I`ll keep you up to date on this whole issue because I know some of you meed answers and some of you are just generally interested. I also know that people are blaming various paints for the problem and I know that the answer lies elsewhere.

 

Phil,

 

Could it be that, with the UK climate generally becoming warmer, and certainly with higher rainfall, that the humidity is increasing - and thus the incidence of microblistering therefore increases.

 

If I recall correctly (and my memory isn't what it . . . hmm - - what was I saying) 2009 was considerably more damp than the year prior - - and that may explain the rash of microblistering in recent months.

 

(I've even suffered microblisters with my domestic painting (using oil-based quality gloss) - and eventually worked out that was caused by allowing the undercoats to remain in humid conditions before the top coats were applied.)

[NB Alnwick]

Phil,

 

Could it be that, with the UK climate generally becoming warmer, and certainly with higher rainfall, that the humidity is increasing - and thus the incidence of microblistering therefore increases.

 

If I recall correctly (and my memory isn't what it . . . hmm - - what was I saying) 2009 was considerably more damp than the year prior - - and that may explain the rash of microblistering in recent months.

 

(I've even suffered microblisters with my domestic painting (using oil-based quality gloss) - and eventually worked out that was caused by allowing the undercoats to remain in humid conditions before the top coats were applied.)

 

I always rub down wet with very fine wet and dry paper to make a good bond between coats. The abraided surface gets thoroughly soaked but I allow it to dry properly before re-coating and have not suffered from micro-blisters in the paint yet - but then I have not tried to apply paint during damp or humid conditions . . .

[rubblequeen]

Due to get someone to paint my boat after this summer - seems that I need to insist or find a painter who will keep the place dry and warm using infra red heaters. And not deal with anyone using paraffin heaters.

 

Have I got it? Or should I be looking for other things?

 

This has been so helpful to me as a newbie.

Thanks Tony

[Phil Speight]

Due to get someone to paint my boat after this summer - seems that I need to insist or find a painter who will keep the place dry and warm using infra red heaters. And not deal with anyone using paraffin heaters.

 

Have I got it? Or should I be looking for other things?

 

This has been so helpful to me as a newbie.

Thanks Tony

I`m afraid it isn`t proving that simple. Our sample of boats from Yorkshire through Leicestshire, Worcestershire and Warwickshire ( ones with our paint and others ) hasn`t thrown up an identifiable pattern or set of conditions yet. That is where the mystery lies other than the frequency with which the problem has been occurring. I`ll keep adding to tgis issue as and when I have something new to say.

Phil

[Phil Speight]

Due to get someone to paint my boat after this summer - seems that I need to insist or find a painter who will keep the place dry and warm using infra red heaters. And not deal with anyone using paraffin heaters.

 

Have I got it? Or should I be looking for other things?

 

This has been so helpful to me as a newbie.

Thanks Tony

I`m afraid it isn`t proving that simple. Our sample of boats from Yorkshire through Leicestshire, Worcestershire and Warwickshire ( ones with our paint and others ) hasn`t thrown up an identifiable pattern or set of conditions yet. That is where the mystery lies other than the frequency with which the problem has been occurring. I`ll keep adding to tgis issue as and when I have something new to say.

Phil

[Water Rat.]

This has been very informative, thank you. Jade has developed micro blistering on the roof, she was painted last summer. I thought it might have been the snow lying on the roof - I did not notice the problem before the winter, just a little patch under the cover where moisture can be trapped. Does this mean the roof will have to be rubbed down and done again?

[Phil Speight]

This has been very informative, thank you. Jade has developed micro blistering on the roof, she was painted last summer. I thought it might have been the snow lying on the roof - I did not notice the problem before the winter, just a little patch under the cover where moisture can be trapped. Does this mean the roof will have to be rubbed down and done again?

I suspect, or am beginning to suspect, that in one or two cases the snow, turned to ice at the bottom, is a factor in some cases. It would certainly cause moisture to be locked in against the paint and that would cause a problem in the particularly unusual conditions we`ve had this winter. Do nothing until the problem has stopped spreading. When it is stable get in touch, answer a few simple questions for me ( because there are variables to consider ) and I`ll tell you what to do.

Edited January 29, 2010 by Phil Speight

[Ally]

This has been very informative, thank you. Jade has developed micro blistering on the roof, she was painted last summer. I thought it might have been the snow lying on the roof - I did not notice the problem before the winter, just a little patch under the cover where moisture can be trapped. Does this mean the roof will have to be rubbed down and done again?

The problem seems to often start on the roof from what I understand.....it may be worth waiting to see if it develops any further to the cabin sides before you take any action.

[Phil Ambrose]

Micro Blisters are not just something effecting steel boats, I have painted my 40ft GRP boat twice now and even trying to get the timing right with regards to temp, weather, humidity I have still had the problem. I have just learnt to live with it, rub down and apply fresh untill I am happy with the result.

It seems to me that it is nobody's fault but "just one of those things" after all, Life is a bitch and then you die!

 

Phil