Micro-blistering

[Phil Ambrose]

Biggles have you approached the paint manufacturer or is that a silly question?

 

Phil

[Biggles]

Oh Yes!!!!

 

They are being very unhelpful as you can imagine. The legal stick has been waved.

[Ally]

There is some new guidance about Microblistering out last week, from the BMF. I understand it is also on their website for those of us with access. I have it in an email and have just asked for permission to share it (don't want to risk any legal iffyness!) so if I get permission, I shall copy it through to here for you all.

[billS]

Is microblistering really a problem?

 

We bought our boat 5 years ago, and it had a red and green re-paintjob which was 2 or 3 years old at the time. The red parts were faded and I needed the previous owners name covered (see my avatar). When this was done, we polished the boat with Craftmaster polish, and I was horrified to find extensive microblistering on the green cabin sides.

 

5 years later, with 2 polishes per year, the sides are just the same. The microblisters have got no worse, and are really only discernable by touch.

 

Hence my question, or is my case unusual?

[Ally]

Generally it tends to be more a cosmetic issue than an actual structural issue, so if it's a 'problem' depends on your nature really. That said, the pictures above...the ones around the window, look more like a rust spread issue than simple micro-blistering IMO.

 

I have had permission now to reproduce the following guidance:

 

"Painting or repainting steel boats in the traditional manner can lead to problems of paint micro-blistering or moisture blistering. One of the main causes of this phenomenon is osmotic pressure developed by the action of water soluble salts between the different layers of the coating. This situation can be generally attributed to the saturation of the film by exceptional levels of atmospheric humidity, together with the presence of water-soluble materials, either absorbed into the film or present on the surface before painting.

Thus any paint film can blister if the weather conditions are severe enough regardless of when the paint was applied; stimulated by conditions where large amounts of rain and snow, combined with high humidity and short spells of sunshine, prevent moisture from completely drying out on the paint film. It should be remembered that steel has a high specific heat value, and so will remain cold for a long time after the local environment has warmed up, thus aggravating dampness and condensation issues.

Leading paint manufacturers typically work to very high standards of paint technology in the formulation of topcoats, primers and thinners, but no paint film is completely impervious to water, water vapour or industrial pollution. In particular the traditional alkyd based enamel paints used in the inland waterways industry have poor resistance to long term water immersion and exposure. Under normal conditions such paints offer a good cost to finish ratio, however severe weather conditions such as those experienced during the winters of 2010/11 have contributed to an increase in prolonged exposure to moisture.

Paint manufacturers’ guidance for their paint application requires a working environment and conditions that are difficult to achieve other than in a closed, heated and humidity controlled workshop which is also free of dust and any possible contamination from other work.

However, Boatyards rarely have such dedicated facilities and the cost of transporting boats to such a facility would be high. Therefore, whilst Boatyards can make every effort to ensure the best quality work is carried out during painting, experience shows that there is always a risk of micro-blistering occurring, particularly when repainting."

So nothing very new there, but that is what we have been sent.

[ditchcrawler]

I knew it was my fault for leaving the boat out in the rain. In days of old paint protected steel from rain, now paint needs protecting from rain.

[Ally]

Indeedy!

[bizzard]

Is microblistering really a problem?

 

We bought our boat 5 years ago, and it had a red and green re-paintjob which was 2 or 3 years old at the time. The red parts were faded and I needed the previous owners name covered (see my avatar). When this was done, we polished the boat with Craftmaster polish, and I was horrified to find extensive microblistering on the green cabin sides.

 

5 years later, with 2 polishes per year, the sides are just the same. The microblisters have got no worse, and are really only discernable by touch.

 

Hence my question, or is my case unusual?

This could be due to what I described in my post 104 . I never wax polish my boat for that reason only wash it. Rylards paint I find is very tolerant to paint with if the atmosphere is cold or possibly feeling a bit damp. I after rubbing down, wipe over with white spirit which will help to evaporate any dampness, let that dry and paint immediately!!, don't dither about gassing and drinking tea cos any dampness, humidity or airborne oily muck like traffic or aircraft exhaust fumes will be settling on it. The air is dirty that's why we have hairs up our nostrils to filter it and also if you leave the lid off a jar of jam and let the so called fresh air get in the jam goes bad. . I always prepare an area, say a 3metre square which I can handle easily and work on it non stop to a finish, rubbing down (de-nibbing) between each coat and them move on and start another. Its risky preparing say the whole boat or a whole side at once due to the time delay of getting the paint on, even indoors cos that nasty dirty air gets in there too,

[Phil Ambrose]

Biz you are right about airborne contaminants, I used to moor near a huge Willow and one day having just finished painting my roof a squall came from nowhere and dumped a huge anount of leaves on the fresh paint

So glad of the hairs in my nostrils

 

Hadto pick the leaves off with tweezers!!

 

Phil

[bizzard]

Biz you are right about airborne contaminants, I used to moor near a huge Willow and one day having just finished painting my roof a squall came from nowhere and dumped a huge anount of leaves on the fresh paint

So glad of the hairs in my nostrils

 

Hadto pick the leaves off with tweezers!!

 

Phil

Yes and all those thousands of insects buzzing around will be emptying their bladders willynilly all over the shop too, I can't see em flying about then suddenly crossing their legs in midair and holding it when they espy someone painting their boat below, they've not got the brain to realize or understand paint blisters.

[Guest]

Yes and all those thousands of insects buzzing around will be emptying their bladders willynilly all over the shop too, I can't see em flying about then suddenly crossing their legs in midair and holding it when they espy someone painting their boat below, they've not got the brain to realize or understand paint blisters.

Or have they?

[Tonka]

Surely if this is true then paint is not fit for purpose and as such we should sue the manufacture

[Guest]

Didn't some problems emerge with certain paints after EU insisted that certain additives were reduced? Seem to recall reading something along these lines.

[peterboat]

We have 3 car paint shops within 100 meters of my garage none of them use wet and dry all prep is done dry and of course the cars are in ovens so moisture is never an issue. do they get micro blistering? nope I did my boat the same apart from the oven (allthough in July of this year it was that hot I didnt need one) I sprayed in a dry dock under cover and as yet no micro blistering, To be honest you have to do everything dry if you dont want problems later on

 

Peter

[Guest]

We have 3 car paint shops within 100 meters of my garage none of them use wet and dry all prep is done dry and of course the cars are in ovens so moisture is never an issue. do they get micro blistering? nope I did my boat the same apart from the oven (allthough in July of this year it was that hot I didnt need one) I sprayed in a dry dock under cover and as yet no micro blistering, To be honest you have to do everything dry if you dont want problems later on

 

Peter

Interesting. I do all sanding dry because I use an electric sander.

[NorthwichTrader]

I sanded my 70ft boat by hand with wet & dry! 600 paper would clog in no time without water, wouldn't it?

[Higgs]

I sanded my 70ft boat by hand with wet & dry! 600 paper would clog in no time without water, wouldn't it?

 

If you use wet and dry, you'll have to use water.

 

May I suggest - a Metabo SXE 450 Turbo tec. Connected to a vacuum. 120, 240, 320, 400 grit disks. Surface wipe and Tak rags.

 

The moment you start on the job with dry sanding, and with the orbital, you can tell when the paint is ready for sanding. If it isn't, you won't be able to sand without the disks clogging, you'll find that you'll create large particles of paint. If it's ok, you'll just have very fine dust and most will be collected down the vacuum.

 

The Metabo isn't cheap, but it's a real work horse. It will take alot of hammer, as long as you don't use constant pressure on the edge - which will kill the bearing.

Edited October 13, 2013 by Higgs

[NorthwichTrader]

Many thanks for that, Higgs! I wouldn't do it by hand again, that's for sure!

[Phil Speight]

I`ve spent the thick end of 4 years researching the various causes of micro-blistering. This has involved driving bloody miles to look at boats , painting facilities and to HMG Paints " Accelerated Degradation " facility in Manchester. The last element, the willing co-operation between a major manufacturer and myself, has of course caused me to be accused of being "on their side" etc and being part of an industry wide cover-up. Firstly ; I`ve not taken a penny of payment from anyone to ensure that I had an uncontestable right to absolute independence and , Secondly ; HMG have put considerable effort into the project because if there is an intrinsic weakness, almost unique to the painting of canal boats in their products and in synthetic systems as a whole, that has become relatively suddenly to the fore they really do want to know.

 

Unfortunately I rather think I`ve been wasting my time . Yes , there are several demonstrable causes of micro-blisters. Sadly publishing them would not provide the one single answer that many painters and boat owners would find acceptable. They may agree with some whilst vehemently disputing the majority. The paint industry , they already insist, is at fault, and will not admit it because they clearly have a vested interest. No other answer will do. Therefore in fairness I have to point out that painters and their customers also have a vested interest in denying any responsibility. It swings both ways. I have frequently asked for the victims of micro-blistering to actively co-operate with the manufacturers rather than immediately going to war. Only a handful of people have agreed to do so , with extremely useful results.

It may be significant that the painters who have helped me are invariably those who have invested heavily in their business premises in an attempt to reduce the risks of paint failure.

 

The synthetic paint system most of us use and have used for years may well no longer be the ideal - no one is denying that there are better ways of doing the job available nowadays, but it remains the most accessible and practical system given the facilities available to most boat painters. If for some reason it needs to be used slightly differently these days ( possibly allowing longer drying times for instance ) then it is up to the painters to adapt or change materials, but yes, it is perfectly safe to leave synthetics out in the rain, snow , ice etc. 99 times out of 100 if they have been sensibly and diligently applied and the owner has taken on serious responsibility for the care of his/her own boat.

 

A part of this stream gives a fine example of what I mean. Paint has blistered only where a rust treatment has been applied therefore there must be a failure of either the treatment or the paint, but; one cause of micro-blistering that we isolated years ago is too heavy a coat of certain rust treatments. They should be applied as thinly as possible to prevent them skinning over before they have through dried. Others must be painted over within a short time of their application. Others stick ONLY to rust - so you must rub down all the inevitable areas where they are actually covering the rust free metal that has been exposed around the rust. Fail to comply with any of this and you can expect a failure of the paint film. Material fault ?

 

This is my last communication on this subject you may be pleased to know ! There are an astonishing number of things that can cause micro-blistering. The paint industry as a whole could have been more sympathetic, more communicative and more proactive ( with the honourable exception being HMG at least as far as being proactive is concerned ). It MAY well be that we should now leave paint a little longer between coats, there are a number of potential reasons for this, and not all of them paint or legislation related ,( though I say yet again that synthetic enamels were exempted in 2010 ). IF this is so and IF it is apparent to anyone not working in canal conditions, perhaps we should have been told. However, any competent professional should have been able to spot the necessity. I know a couple who certainly have worked it out for themselves. That however would be relevant in only a small percentage of cases. I would be happy to talk to anyone about all of this - but not here. There is no point,as far as I`m concerned , in going round in endless circles anymore.

I want to help, I WILL help - anyone who is willing to have an amiable and constructive discussion. So talk to me the old fashioned way by phoning me on 01838 400269. If you then want to pass on the results of our conversation on the forum that`s fine by me. As long as you`re polite about me or keep the insults intelligent and preferably recoverable !

[Biggles]

Thanks Phil. Wise words from one that knows from all ends.

[smileypete]

Did a web search the other day, found a couple of references on micro blistering, one from HMG:

 

http://www.hmgpaint.com/knowledge-base/blistering-the-causes-and-prevention

 

http://www.metalfinishing.com/view/21322/osmotic-blisters-in-coatings-and-adhesives/

 

Looks like the root cause is water soluble contamination or paint ingredients - possibly uncured or unreacted?. Maybe at least partly down to errors in preparation or application.

 

I suspect quite a few cases are down to a minimal job in less than perfect conditions, which might work, or might not. I wonder if a high build primer would help here, at least on roof and decks, but it'd add cost.

 

BTW Biggles why does your sig say:

 

Until Dan gets his act together, you can donate to the running costs of the CanalWorld forum via Paypal using the button at the bottom of this page

 

Don't you think that's a tad rude? Maybe for some good reason Dan's decided not to have donate buttons all over the place, at least for now.

 

cheers, Pete.

~smpt~

[Biggles]

No. I have simply copied it from another member. I doubt Dan would be offended. If he is I'm sure I and the other members carrying this message would be PM'd.

 

I can however see your point.

[Steve Goddard]

_{Have just caught this thread and would like to add a couple of thoughts}

 

_{1: I can attest from personal experience that if you have an issue and approach it in the right way that the paint manufacturers, the painter (in my case HMG and John Barnard) and Phil will actually do everything that they can to try and identify the cause of the problem. After all it really is in all their interest. The difficult bit is determining what is the root cause as there is NO SIMPLE answer. I now know far to much about paint chemistry, paint systems, paint testing methodology and paint failure modes than is compatible with retaining your sanity. Honestly from my experience I simply can not ascribe to any of the multiple conspiracy theories regarding a cover up by paint manufacturers.}

 

_{2: Now for the controversial bit :- you know I suspect that there has always been microblistering/blistering and that it is not just a recent phenomenon. What, however is a recent phenomenon is the surge in social media allowing the whole issue to be more widely disseminated and debated (just look at the numerous threads on this forum). Go back five years and there was simply no way for people who were affected by this to see that they were not unique and also I guess no real way for the industry to see the full extent of the problem. These days everybody knows about microblistering (and is willing to tell you what causes it). My two cents worth ..}

[ditchcrawler]

Well the last time my boat was painted it didn't blister, this time it did.

I used a painter recommended by a friend, he had done their boat many years before and apart from damage it was still sound.

[Phil Speight]

So - my last post was not, after all the very last. Here`s another last post to follow the first last post I`m ever going to etc. etc!

 

I think I should have tried to be more helpful, so I shall. Incidentally , for those who may think otherwise, far more boats remain blister free than those that don`t. We just tend not hear about them.

 

There are three ways in which micro-blistering can manifest itself. The blisters are merely the obvious symptoms, the actual causes are many and varied, and in some cases quite surprising. I`m not going to list them here because I have no wish to start a debate. Instead I`ll try to suggest ways in which one can try to avoid the problem. So;

 

1. Micro-blistering caused by moisture entrapment.

2. " " " " solvent retention.

3. " " " " surface penetration.

 

To guard against the first try to allow steelwork time to acclimatize in the dock before starting to paint. Keep the ambient temperature as constant as possible. beware of high humidity ( it can measured } and do not paint anywhere near the due point on any given day. This can also be predicted electronically. Remember, condensation can form on bare steel UNDER the primer if it has not through dried at the critical atmospheric point.Other than all this , use your brain - if the air is damp - don`t paint.

 

No 2- do not re-coat until you KNOW that the previous coat is thoroughly dry. Drying rates will vary day to day. If you panel wipe/degrease the bare steel allow it time to warm up again afterwards. The flashing off of the solvent you have used will have reduced the surface temperature of the steel by up to 6 degrees. NEVER de-grease or introduce solvent to fresh paint before re-coating. Some of it will be drawn into the film and could well become trapped there.

 

AND 3 - THE CONTRAVERSIAL ONE!If there is sufficient film thickness on clean and uncontaminated full gloss enamel on cabin sides and so on - it should not suffer from surface penetration of moisture. Only where water cannot drain and pools instead should you expect a problem. However, matte , satin and textured finishes do not allow water to drain as readily as full gloss. They are therefore more vulnerable. My old colleague John Sanderson and myself habitually put a full gloss finish on any surface that is to have one of these vulnerable finishes. We worked together for 17 years and I can`t remember a time when we did not do this.REMEmBER - FILM THICKNESS = 200 microns plus is wonderful, 150 to 200 is absolutely fine, 130 to 150 is good enough. Less than that and you`re asking for problems.

 

This is by no means comprehensive and it does not cover several causes of micro-blistering that have been isolated in recent years - but I hope it helps someone somewhere to avoid the problem.