Micro-blistering

[Higgs]

 

This was a quick snap taken without cleaning. The patterning is dust formed under some of the rubber hole non slip dash stuff.

 

When I'm at the boat next I will take it again and show an area thats not blistering that didn't have Rustcote used on it as it was filler.

 

The patterning left by an uncleaned deck is not important in itself, it is evidence that matting was down; a moisture trap, trapped moister leads to microblistering.

 

If the blistering extends beyond the area of matting, then, you could say that the matting wasn't solely responsible for the blistering on that deck area.

Edited October 7, 2013 by Higgs

[Biggles]

 

The patterning left by the rubber matting is not important, it is evidence that matting was down; a moisture trap, trapped moister leads to microblistering.

 

I can see how you would think this but this is undercover and is dry. The mat was put down to hide the blisters. Its definitely not the cause of it. The full picture will show more when I take it later this week.

[Higgs]

 

I can see how you would think this but this is undercover and is dry. The mat was put down to hide the blisters. Its definitely not the cause of it. The full picture will show more when I take it later this week.

 

That's that one scuppered then.

 

Have you burst a few blisters and sniffed and found a chemical smell or found water inside?

[bizzard]

I know this is probably not the same as the blisters but wax polishing on especially a flat surface like a roof will cause rain water to divide up into lots of small globules which when the sunlight is strongly shining upon em act like wee magnifying lenses and can scorch the paint below leaving peppered permanent polka dot pale spots when dry. This was very common on vehicles years ago painted with cellulose paint, again often red colours.

[Troyboy]

Woolworths Household paint used to be excellent too and you could get it in small tins if you only needed a small amount.

When I bought my boat in 1986 it was painted in Woolworths paint and I continued to use Woolworths paint for years but eventually they must have changed supplier or formula because the quality was much inferior . I then changed to International Brightside but they no longer make that so my boat is now half Brightside and half Dulux Weathershield exterior gloss .

[bizzard]

When I bought my boat in 1986 it was painted in Woolworths paint and I continued to use Woolworths paint for years but eventually they must have changed supplier or formula because the quality was much inferior . I then changed to International Brightside but they no longer make that so my boat is now half Brightside and half Dulux Weathershield exterior gloss .

I think it was when the lead content was removed that Woolworths Household paint went down hill. Indeed Brightside polyurethane paint was good, well pigmented, covered well and dried reasonably quickly.

 

Personally I used Rylards now which I find whilst painting outside is the most forgiving in cold or maybe slightly damp conditions.

Edited October 7, 2013 by bizzard

[Alastair]

That sounds a bit odd, the anodes are surely already 'earthed' by being attached to the hull? Plus, sitting in 'free space' rather than water there can be little or no reaction going on?

I suspect it's more coincidence than cause/cure, but it would be interesting to hear from someone who really knows about such things. Maybe properly earthing the hull, which is what earthing the anodes would effectively do, might conceivably have some effect but it sounds highly improbable.

 

Tim

Earthing the anodes (and hence hull) could stop static buildup on the boat.

 

What could cause static build up?

 

Repeated brushing.

[Beaker]

Woolworths Household paint used to be excellent too and you could get it in small tins if you only needed a small amount.

 

Yes, I believe Woolworths paint was made by Macphersons, a good brand.

[kitman]

This is an extreme example of my mico blistering.

 

 

This is not so much mico but its shows what happening smaller elsewhere.

 

Is this section on the roof under the pram hood? If so, is the roof heavily blistered immediately forward of where the pram hood ends? Or does the amount of blistering subside after the pram hood?

 

Was this one of the sections that you used the vactan (or similar porduct) on? What was the steel like that you rust treated? Was it heavily pitted steel?

 

IMO rust converters are not good enough to have any real beneficial effect on pitted steel, I've seen quite a few cases like this.

 

That's that one scuppered then.

 

Have you burst a few blisters and sniffed and found a chemical smell or found water inside?

 

My money is on finding black/dirty wet rust underneath

[Biggles]

 

Is this section on the roof under the pram hood? If so, is the roof heavily blistered immediately forward of where the pram hood ends? Or does the amount of blistering subside after the pram hood?

 

Was this one of the sections that you used the vactan (or similar porduct) on? What was the steel like that you rust treated? Was it heavily pitted steel?

 

IMO rust converters are not good enough to have any real beneficial effect on pitted steel, I've seen quite a few cases like this.

 

My money is on finding black/dirty wet rust underneath

 

 

The steel had been allowed to rust for several months to dissolve the mill scale. It was then rubbed down with a large belt sander, then DA'd then the Rustcote was applied. http://boatbuildblog.blogspot.co.uk/2010/05/finally-got-something-to-blog.html

 

 

This is the rear of the roof where the canopy was eventually fitted. All the prep was done to the info sheet specification.

 

The cabin sides were done the same.

 

 

The rest of the roof did microblister using pain supplied by the same supplier but I covered it with a heavy grit antislip. There are 2" seperation arears that still show microblistering I have scraped back to bare with a sharp chissel and this removed a thin film of Rustcote a bit like paint on a bit of tape. I still have a some left to do as its a PITA.

 

Edited October 7, 2013 by Biggles

[kitman]

Thanks for the info biggles. Did you say the sides are blistering too, but not as much? or not at all?

 

I think it would be interesting to do like Higgs says and see what is under the blister, is it dry rust? wet rust? Are they full of liquid?

 

Have you read any articles on acid converters causing blistering to paint films by way of osmosis?

[smileypete]

I think with 2 pack it's very likely best to stick to one manufacturers products, and follow the application guidelines to the letter.

 

cheers, Pete.

~smpt~

[Biggles]

Yes the sides are as well there are some large scabs, but the majority of the problem is tiny tiny microblistering causing a fairly even sheen finish accept where there is filler and there is as shiney as a 2pac finish should be.

 

I will be at the boat tomorrow so I will try and take some photos. I'll take the posh camera.

 

 

This shows the worst but if you look as it moves away from the bad you can see it getting smaller.

[NorthwichTrader]

Crikey biggles, poor you! My micro blisters are really small, not visible above the surface of the paint for the most part (yet)!

I've traced mine down to tiny pin-head sized pits in the steel, would this really be enough to cause this problem? I mark a cross over a blister then chisel it back to steel...each time a pinhead pit between the crosshairs!

[Alastair]

Yes the sides are as well there are some large scabs, but the majority of the problem is tiny tiny microblistering causing a fairly even sheen finish accept where there is filler and there is as shiney as a 2pac finish should be.

 

I will be at the boat tomorrow so I will try and take some photos. I'll take the posh camera.

 

This shows the worst but if you look as it moves away from the bad you can see it getting smaller.

That looks like rust to me. Travelling under the paint from the edge of the steel adjacent to the windowframe.

[ditchcrawler]

There is also a report of micro blistering in Nov Canal Boat pg 43

[Biggles]

That looks like rust to me. Travelling under the paint from the edge of the steel adjacent to the windowframe.

 

I agree it does but its the microblisters joining up The window were put in after the pain so are on to of it.

Thanks for the info biggles. Did you say the sides are blistering too, but not as much? or not at all?

 

I think it would be interesting to do like Higgs says and see what is under the blister, is it dry rust? wet rust? Are they full of liquid?

 

Have you read any articles on acid converters causing blistering to paint films by way of osmosis?

 

OK this is the blue bit in previous photos but with a better camera.

 

 

This shows the same area with a still unpitted section. Under this is body filler where I cut a weld off then sanded out.

 

 

This is the best I could photograph the side.

 

 

Its just occurred to me I should have put something down to scale it. I'll do that tomorrow when its light again.

[Biggles]

I got my macro lense on the job and a penny to scale it.

 

 

 

I just can't get a better photo of the ones on the sides. But they are about 1/5 the size of these but much closer together to produce a matt / sheen finish.

[NorthwichTrader]

I got my macro lense on the job and a penny to scale it.

 

 

 

I just can't get a better photo of the ones on the sides. But they are about 1/5 the size of these but much closer together to produce a matt / sheen finish.

Just out of interest, did you heavily degrease with white spirit?

[Biggles]

Just out of interest, did you heavily degrease with white spirit?

 

No standard thinners

[Phil Ambrose]

Again just out of interest how long did it take for the blisters to appear after you finished painting?

 

Phil

[Biggles]

Again just out of interest how long did it take for the blisters to appear after you finished painting?

 

Phil

 

About 4-5 months

[Bod]

Blistering hasn't happened over filler.

Where the filler is feathered out, does the blistering feather in?

Was the filler smoothed exactly the same as the bare metal, or worked differently? (Wet&dry rather than sanded)

 

Would it be worth doing a sacrificial paint job, quick & rough, let it blister as it wants, then rub down, repaint for a final finish.

 

 

Bod

[Biggles]

Blistering hasn't happened over filler.

Where the filler is feathered out, does the blistering feather in?

Was the filler smoothed exactly the same as the bare metal, or worked differently? (Wet&dry rather than sanded)

 

Would it be worth doing a sacrificial paint job, quick & rough, let it blister as it wants, then rub down, repaint for a final finish.

 

 

Bod

 

The filler area is clearly defined in all the (few) areas its been used. The sides have already been resprayed after a year while it was still in build. This was a complete rub down to key things up which removed the blisters. A really thick coat of 2pac was applied (Really thick for 2pac). I have since cut it back once with 1800 wet DA disks then mopped it back to dazzeling. This time it lasted longer but was back in about 6-7 months.

[Higgs]

 

I have since cut it back once with 1800 wet DA disks then mopped it back to dazzeling. This time it lasted longer but was back in about 6-7 months.

 

There's no need to wet and dry. 500 grit is the finest paper you'll need. There's no knowing what contaminants you're introducing with wet and dry. Introducing water into the paint, after removing its waterproofing skin. ??

 

There are some painters who use W and D, but they are using paint every day and would probably go to greater lengths to ensure good conditions. I know that I never wet and dried through 11yrs of painting.

 

I really can't see the need for W and D or any paper finer than 500.