Blacking your hull - an alternative to the usual coatings.

[Laurence Hogg]

We own "Barnet" a Harland & Wolff "Large Woolwich" which is regulary docked and maintained. Back in 1997 we ran out of "blacking" whilst at Bradley dry dock, in a hurry to finish the job we used B&Q trade black to finish the hull off. Several years later in 2007 we grit blasted the hull to bare metal for a total repaint. Everything came off easily - except for the B&Q black!!

 

We thought this was odd at the time, how come this cheap paint was so tough?

 

Having seen how well it adhered we decided not to use two pack or the usual suspects for "blacking" but to pop down to B& Q and buy a load of trade black. This we did and duly painted the hull.

At the end of 2014 "Barnet" had a major docking and a fair number of repairs were carried out to the hull, we decided that it was time for another coat of blacking. So the team blasted the hull ready for its new coat. It actually didn't need one, the B&Q black was in most cases as sound as the day it went on in 2007! Well we were surprised, ok where the new metal was we had to paint that but this cheap black paint had stood the test of time yet again.

We popped off down to B&Q and purchased the next lot and duly repainted the hull, if it lasts this well its doing a grand job of protecting the steel, and better still what else will paint a 71ft hull for just under £120?

 

A lesson to be learned here, how many of the common used blacking compounds are actually designed for inland waterway use? Most aren't, they are for salt water protection where "contact" with other surfaces is unknown as such, hardly comparable to a canal boat's amount of contact.

 

I would seriously reccomed this paint to anyone blacking their hull, its done a cracking job on ours and some of the 1997 paint is still there today.

[valrene9600]

Is trade black just thin paint or is it their version of a bitumen product.

[blackrose]

I find out difficult to believe that any bitumen based paint would last for 7 years without coming off in places along the waterline, and that's where it's important. I've still got 5 year old Rylards blacking in good condition on my hull, but it's also come away in patches on the waterline.

 

Is this the stuff?

http://www.rooftrade.co.uk/products/paints/b-q-universal-black-bitumen-paint-2-5l-45-detail.html

Edited January 9, 2015 by blackrose

[Alf Roberts]

I find out difficult to believe that any bitumen based paint would last for 7 years without coming off in places along the waterline, and that's where it's important. I've still got 5 year old Rylards blacking in good condition on my hull, but it's also come away in patches on the waterline.

 

Is this the stuff?

http://www.rooftrade.co.uk/products/paints/b-q-universal-black-bitumen-paint-2-5l-45-detail.html

Lawrence is a lot of things but liar isn't one of them.

[MtB]

Very interesting Lorry, I have two boats needing blacking shortly...

 

Looking on the B&Q website I can't find "B&Q trade black". Does it have a more precise name? Is it paint or bitumen please? Do you find it in the paint department or is it a roofing product?

 

Or maybe I should get out from behind the PC and go and look in a B&Q store...

 

MtB

[c c]

Apart from two pack over the replaced steel beneath the waterline, we've used Wickes black masonry paint for the remaining vast expanse of sides for years. Jus thavn't "come out" until now.

[Machpoint005]

Interesting tale, Laurence -- I thought the main reason for 'traditional' blacking was that in contact with underwater objects it smears rather than scrapes off. Obviously tyour cheap black paint has only been scraped off in a few places, so it doesn't matter all that much after all!

 

Any pre-treatment or undercoat apart from pressure washing?

[peterboat]

I am interested too I am just confirming my docking in July so if it is that good that is what she will get

 

Peter

[Laurence Hogg]

Is trade black just thin paint or is it their version of a bitumen product.

Just an ordinary black paint for general use.

[Machpoint005]

Just an ordinary black paint for general use.

 

Next question -- if the paint was bought in 1997 it probably contained VOCs (oil based) but nowadays AFAIK all B&Q regular paints are water based. Can you actually still get the same stuff?

 

 

 

(spelling)

Edited January 9, 2015 by Machpoint005

[Laurence Hogg]

I find out difficult to believe that any bitumen based paint would last for 7 years without coming off in places along the waterline, and that's where it's important. I've still got 5 year old Rylards blacking in good condition on my hull, but it's also come away in patches on the waterline.

 

Is this the stuff?

http://www.rooftrade.co.uk/products/paints/b-q-universal-black-bitumen-paint-2-5l-45-detail.html

 

No, its just their ordinary black gloss: http://www.diy.com/departments/colours-non-drip-interior-exterior-black-gloss-paint-750ml/183990_BQ.prd

Interesting tale, Laurence -- I thought the main reason for 'traditional' blacking was that in contact with underwater objects it smears rather than scrapes off. Obviously tyour cheap black paint has only been scraped off in a few places, so it doesn't matter all that much after all!

 

Any pre-treatment or undercoat apart from pressure washing?

No pre treatment just pressure blasted and left to dry.

 

Next question -- if the paint was bought in 1997 it probably contained VOCs (oil based) but nowadays AFAIK all B&Q regular paints are water based. Can you actually still get the same stuff?

 

 

 

(spelling)

It appears so, the paint we have is stated as solvent based.

http://www.diy.com/departments/colours-non-drip-interior-exterior-black-gloss-paint-750ml/183990_BQ.prd

 

Edited to add, we have also on occasions used Wickes black (mentioned earlier) and Dulux, both have lasted very well, may possibly be from same manufacturer? who knows, there aren't that many massive paint works around.

 

On "Boatmans Cabin Co" chimneys we used Johnstones (West Bromwich) black gloss and their red paint mixed 50/50 with their red oxide, both proved remarkably heat proof yet were not marketed as such, I know of a few boats which still have our stainless steel chimneys with the original paint, which makes them around 25-30 years old!

Edited January 9, 2015 by Laurence Hogg

[b0atman]

When I did a spell on the slip way the best boats had a grey paint under the blacking quite a smooth finish to it ,With very rarely any exposure of metal.

Maybe Blacking for wooden hulls was a good idea but rigs and bridges are painted trawlers where red leaded.

In a pub discussion the paint used on electricity pylons was discussed .

[Odana]

Interesting. We are booked out for May and pondering products. We have 2 pack (brand unknown) on with many many scrapes and worn patches. Were looking at more 2 pack over the sanded down patches then a coat over the whole lot. Would this stick instead or are we asking for trouble?

[Machpoint005]

 

It appears so, the paint we have is stated as solvent based.

http://www.diy.com/departments/colours-non-drip-interior-exterior-black-gloss-paint-750ml/183990_BQ.prd

 

Thanks -- yes, it says 'high VOC' too, so that answers the question! I didn't know you could still get 'proper' smelly paint!

[jenevers]

When we treated some new (replating) steel on our hull, I was surprised to read on the Bitumen tin instructions, that new steel should be coated with red oxide paint BEFORE applying the bitumen. I was going to apply the bitumen straight onto the new steel. Three years later when we dry docked for re-blacking the hull, the pressure washer blasted the bitumen off no problem but couldn't budge the red oxide!

Makes you wonder if red oxide and a coat of gloss is preferable to bitumen.

[MtB]

When we treated some new (replating) steel on our hull, I was surprised to read on the Bitumen tin instructions, that new steel should be coated with red oxide paint BEFORE applying the bitumen. I was going to apply the bitumen straight onto the new steel. Three years later when we dry docked for re-blacking the hull, the pressure washer blasted the bitumen off no problem but couldn't budge the red oxide!

Makes you wonder if red oxide and a coat of gloss is preferable to bitumen.

 

 

I'm thinking the same. Why DO we always use bitumen blacking? Because 'we always have', perhaps?

 

The main reason I can think of not to use the black gloss Lorry recommends is I'm worried it would make me into a shiny boater

 

 

MtB

Edited January 9, 2015 by Mike the Boilerman

[Graham Davis]

Mike,

Buy some matting agent to add to the paint.

Problem solved.

http://www.ebay.co.uk/itm/like/171237450866?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=108&chn=ps&device=c&adtype=pla&crdt=0&ff3=1&ff11=ICEP3.0.0-L&ff12=67&ff13=80&ff14=108&ff19=0

[Richard10002]

I am planning to lift out in Spring and was thinking about what to use on the bottom, (sides actually, as we seem to not be too bothered about painting the bottom).

 

I wondered why we use a bitumen based "blacking", when on seagoing boats I would use a coat of International Primer, then an antifoul of some kind.

 

As we also dont seem to be worried about antifouling on canals, I then wondered why not just use a decent quality exterior paint over a suitable undercoat.

 

I'm not sure what was used when I had it "blacked" in 2011 when I bought it, so not sure what kind of preparation and undercoat would be suitable.

 

I think a few of the boats in our club have used Wickes bitumen based roofing stuff. I saw a couple of 75l barrels knocking about.

[blackrose]

Lawrence is a lot of things but liar isn't one of them.

Thank you for that. I don't think I called him a liar. Perhaps you should read posts properly before replying.

 

As it turns out I was correct because it isn't a bitumen-based paint that Laurence was using.

Edited January 9, 2015 by blackrose

[blackrose]

I'm thinking the same. Why DO we always use bitumen blacking? Because 'we always have', perhaps?

 

MtB

The main reason I think we don't normally use ordinary gloss paint below the waterline is because it isn't designed for underwater applications, is it?

 

How come it works?

When we treated some new (replating) steel on our hull, I was surprised to read on the Bitumen tin instructions, that new steel should be coated with red oxide paint BEFORE applying the bitumen. I was going to apply the bitumen straight onto the new steel. Three years later when we dry docked for re-blacking the hull, the pressure washer blasted the bitumen off no problem but couldn't budge the red oxide!

Makes you wonder if red oxide and a coat of gloss is preferable to bitumen.

My understanding it's that most red oxides are porous and aren't suitable below the waterline. If you want an underwater primer try International Primocon. I've used it several times and it's good.

[Bee]

Strange. I have 2 pack epoxy below water and black gloss (not water based) above. The black gloss is a mess, scrapes, scratches and damage everywhere and it looks as though I have hit every wall and rock for hundreds of miles, I was thinking of some sort of bitumen paint to cover the whole thing up. More research for me I think.

[Richard10002]

Primocon is what I used to use on a seagoing GRP yacht, before antifouling. It was reputed to grip to anything, form a good barrier, and a good base for the topcoat.

 

I dont know enough about paints to know if it would work fine over previous blacking, and what would be a better topcoat for a narrowboat.

[Neil2]

The reason why we don't use alkyd, or even modified alkyd resins on hulls is because these paints are supposed to deteriorate very quickly once immersed in water for any length of time.

 

Must admit I find most so-called exterior paints quite disappointing even when used in "normal" applications so the idea of using this stuff in place of standard blacking calls for a lot more evidence before we all start changing our views.

[blackrose]

Primocon is what I used to use on a seagoing GRP yacht, before antifouling. It was reputed to grip to anything, form a good barrier, and a good base for the topcoat.

 

I dont know enough about paints to know if it would work fine over previous blacking, and what would be a better topcoat for a narrowboat.

Primocon does work as a tie layer between different paints but I've mainly seen that as a benefit when patch priming, rather than painting it over an entire previous coat of blacking. I can't really see the point of that.

Must admit I find most so-called exterior paints quite disappointing even when used in "normal" applications so the idea of using this stuff in place of standard blacking calls for a lot more evidence before we all start changing our views.

I tend to agree. It will be interesting to see if other users of black gloss instead of blacking experience similar results to Laurence.

[jenevers]

 

My understanding it's that most red oxides are porous and aren't suitable below the waterline. If you want an underwater primer try International Primocon. I've used it several times and it's good.

 

That was my understanding too. But there was no rust or pitting under the red oxide. Maybe it was a GLOSS red oxide and therefore not porous.