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Troyg

Which 2 pack for blacking??

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Hello all.

I am sure this topic has already been discussed several times.....

I am soon having my narrowboat shot blasted and plan to apply 2 pack. I have recently purchased the boat and it has been neglected and not blacked often. This means the hull, although structurally sound has suffered pitting which needs to be halted. Hence the reason for going down the 2 pack route.

However which 2 pack to use?? There seems to be a minefield of choice....Hempel Hempadur 45143, Interzone 954, Intertuf 362 just to name a few.....

I will be applying it myself and will want something suited to adhere well to a pitted hull and provide a good protection. I am happy (and probably prefer) to do a couple or more coats.

Also would anyone have an idea of how many litres would be needed for a 60ft narrowboat hull?

 

 

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Personal recommendation, based on very satisfactory  experience, Sherwin Williams of Bolton 011204 521771.   L524B Base Black and L524A Additive.

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Its really difficult to know which is best as there are no back to back scientific tests, all boats are different and preparation and boat use can be big factors. I expect everybody on the forum will recommend the one that they have used.

We are done in the Intertuf one because that's what the yard liked to use. I also note that Midland Chandlers stock it but would not see that as any sort of recommendation. In a few places it has scraped and abraded off. I know some boaters who say that other brands are still perfect after ten years, but then we do over a 1000 miles a year and a lot of locks. A protruding lock collar will almost certainly take anything off if you scrape it hard enough.

I know people say it lasts ten years but I reckon to come out of the water every three years, derust any damaged bits and get another couple of coats on. Some would say this is not good value as ordinary blacking last two years, the difference with epoxy is that after three years 99.5% of it is still on and there is no pitting.

.............Dave

 

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A good 2 pack epoxy will last for years if applied to a shot blasted surface ( to SA 2 1/2) but how are you going to achieve that. In any British summer, rust formation starts within hours and you will get a rust bloom. You need to get a first wash coat on as it is being blasted ie same day. That's how the professionals do it.  If you are not going to get an SA 2 1/2 surface to paint on then look for a 2 pack epoxy that has some surface tolerance to rust bloom.

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I don't think this is a major issue, the yard who did ours have a covered dock and also used side sheets to keep any weather out, but mostly to keep the mess in.

They prepared everything in the afternoon, mostly fitting a big sheet over the cabin and blocking every possible hole, the next morning they shot blasted and by mid afternoon had the first coat of epoxy on.

...........Dave

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3 minutes ago, dmr said:

I don't think this is a major issue, the yard who did ours have a covered dock and also used side sheets to keep any weather out, but mostly to keep the mess in.

They prepared everything in the afternoon, mostly fitting a big sheet over the cabin and blocking every possible hole, the next morning they shot blasted and by mid afternoon had the first coat of epoxy on.

...........Dave

Dave, sorry my post was not aimed at you. It was for the OP to consider. If he too is doing it like you then he will have little problem......but some yards dont work like that.

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3 minutes ago, Dr Bob said:

Dave, sorry my post was not aimed at you. It was for the OP to consider. If he too is doing it like you then he will have little problem......but some yards dont work like that.

Yes, this a job that its probably better to pay a yard to do rather than DIY as they can throw labour at it so that it happens quickly. Two people did the shot blasting, one did the actual work whilst a second generally watched over and made sure the air supply was ok, then two people put the epoxy on.

We used to do our own blacking but the savings are not that great, the dock rental can cost a fair bit whereas a yard can do a sort of package deal for the whole project. We lived on the boat in the dock but obviously had make ourselves scarce during the blasting.

 

..............Dave

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44 minutes ago, Dr Bob said:

A good 2 pack epoxy will last for years if applied to a shot blasted surface ( to SA 2 1/2) but how are you going to achieve that. In any British summer, rust formation starts within hours and you will get a rust bloom. You need to get a first wash coat on as it is being blasted ie same day. That's how the professionals do it.  If you are not going to get an SA 2 1/2 surface to paint on then look for a 2 pack epoxy that has some surface tolerance to rust bloom.

We use to achieve that out in the North Sea. Watch the weather forecast, spend a day blasting the old paint off, next gay if conditions looked favourable the light blast again to remove overnight rust, this would bring you to lunch time, by now hopefully the dew point, steel temperature and every thing else would be with you so air less spray Sigma Coatings 2 pack on. measure wet film thickness as you go. This required a team of blasters, kettle men, sprayers, paint mixers and the paint inspector who's job it was to make sure it was all in spec. A lot of time was spent watching the TV

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All good advice, Jotumastic 87 is supposed to be 'surface tolerant' so less than perfect surface could be ok. I think Jotun may even say filling pits is OK but you'd have to check. I have used Sigma for the last 10 yrs but think that they may have changed the formulation of the stuff that I used - had a problem a few years ago when I used it in Holland as the yard where I did it were not happy as it was coal tar based and banned from Dutch waters. Anyway I have got a stack of Jotumastic 87 in the kitchen waiting to go on the boat in a week or so and hopefully it will be OK.

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The EU has recently (ish) banned coal tar based products so lot of two packs have either changed formulation or are no longer available.

I spoke to one manufacturer this morning about what their recommended replacement was for their now discontinued pitch epoxy product, and was told bitumen.

Most manufacturers won't warrant their product on top of anyone else's, so I fear a lot of people are going to end up re-blasting much sooner than intended for peace of mind.

The reality is that some of products will work over the older ones - but it's going to take a few years and some hard lessons to find out which.

A word of caution with Jotamastic 87 - recommended drying time is 7-14 days at UK ambient temperatures.

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15 minutes ago, Rose Narrowboats said:

A word of caution with Jotamastic 87 - recommended drying time is 7-14 days at UK ambient temperatures

I used the Winter grade on our engine room last summer,2-3day curing time at 10-23 Degrees C according to the data sheet.

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58 minutes ago, Rose Narrowboats said:

The EU has recently (ish) banned coal tar based products so lot of two packs have either changed formulation or are no longer available.

 

That's a real shame. Coal tar epoxies were one of the best two pack systems for water/air contact - they were the ones used on most splashzone areas on offshore rigs in the 80's & 90's. The real Bees knees of coatings. I know coal tar is considered carcinogenic but it is carefully controlled in the paint industry. Another good coating bites the dust.

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Opinions certainly vary. At the moment I am leaning towards Hempel Hempadur 45143. I read that it is also surface tolerant. The drying times for the Jotamastic 87 put me off. The Sherwin Williams could be an option but doesn't seem that common? And which one to use? I assume the Macropoxy M922? Not much info for it if surface tolerant and resists oil etc.

Decisions to make but the 45143 is leading currently.....

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25 minutes ago, Troyg said:

Opinions certainly vary. At the moment I am leaning towards Hempel Hempadur 45143. I read that it is also surface tolerant. The drying times for the Jotamastic 87 put me off. The Sherwin Williams could be an option but doesn't seem that common? And which one to use? I assume the Macropoxy M922? Not much info for it if surface tolerant and resists oil etc.

Decisions to make but the 45143 is leading currently.....

https://www.paintdocs.com/docs/webPDF.jsp?SITEID=BOLTON_EX&prodno=M922A&doctype=PDS&lang=en_GB

Capture.JPG

Capturea.JPG

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I have just finished mine with Andrews two pack epoxy coal tar black. It has been two pack since new so no need to shot blast. Its good stuff easy to use but better when the steel is warm.  Having purchased the boat in January last year I wanted to make sure all was well underwater. The previous coats were still in excellent condition below the waterline.

Three 2.5 ltr tins did two complete coats above and below the waterline, with enough left to do two more coats below the water line, and about a quarter of a tin left. Mine is 47ft.

Andrews service was very good with the delivery three days after order. I have no connection to them only as a satisfied customer. I did the work myself using one tin per day waiting until the steal was as warm as possible. It makes a real difference. I used a lot of cheap very stiff paintbrushes probably three per tin. Make sure when you mix the two parts you are going to use it all. After six hours or so its getting very thick in the bottom of the tin.

I am very satisfied with the result.

Good luck Johnh

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19 minutes ago, John Hartley said:

I have just finished mine with Andrews two pack epoxy coal tar black. It has been two pack since new so no need to shot blast. Its good stuff easy to use but better when the steel is warm.  Having purchased the boat in January last year I wanted to make sure all was well underwater. The previous coats were still in excellent condition below the waterline.

Three 2.5 ltr tins did two complete coats above and below the waterline, with enough left to do two more coats below the water line, and about a quarter of a tin left. Mine is 47ft.

Andrews service was very good with the delivery three days after order. I have no connection to them only as a satisfied customer. I did the work myself using one tin per day waiting until the steal was as warm as possible. It makes a real difference. I used a lot of cheap very stiff paintbrushes probably three per tin. Make sure when you mix the two parts you are going to use it all. After six hours or so its getting very thick in the bottom of the tin.

I am very satisfied with the result.

Good luck Johnh

Interestingly it seems to be still available. I'll be ringing them in the morning :)

EDIT to add - apparently coal-tar products havn't been banned yet. According to this https://www.ecomundo.eu/en/blog/reach-authorisation-coal-tar-pitch the ban doesn't come into force until next April. All of our usual suppliers have already stopped making products using it though.

Edited by Rose Narrowboats

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11 hours ago, Dr Bob said:

A good 2 pack epoxy will last for years if applied to a shot blasted surface ( to SA 2 1/2) but how are you going to achieve that. In any British summer, rust formation starts within hours and you will get a rust bloom. You need to get a first wash coat on as it is being blasted ie same day. That's how the professionals do it.  If you are not going to get an SA 2 1/2 surface to paint on then look for a 2 pack epoxy that has some surface tolerance to rust bloom.

Jota mastic 87 as suggested above is one of the most surface tolerant 2 pack epoxies and one of the easiest to apply. 

The main thing to remember is to mix the paint thoroughly before adding part b, mixing thoroughly to the correct proportions by volume and to pay attention to minimum and maximum overcoating times. 

I used two coats of jotamastic 87 with aluminium followed by two coats of standard jotamastic 87 black. This will turn grey over time so if you want it black you need a coat or two of Jotun Hardtop to finish instead. 

Use winter grade hardener even in summer unless you can afford to keep your boat out of the water for a week after you finish! Curing will stop once the boat is reimmersed and the temperature drops. 

https://www.jotun.com/we/en/b2b/paintsandcoatings/products/jotamastic-87.aspx

You will need to download the relevant data sheets. All available with a Google search. 

Edited by blackrose
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My local chandlery only had one 2 pack epoxy in stock, interzone 954. Read up on it's performance and it was quite encouraging so decided to use it on my boat.

 

I did the preperation myself as the dock doesn't allow blasting, it was quite time consuming but got the important areas covered in the end ie. waterline, weld seams, badly pitted areas etc.

 

It's been on 2 years now and there are no visible signs of any failure. It's going back in the dock in July so I should have a better idea of it's performance and treat some of the areas that didn't get done last time.

No need to worry about drying times with 954, it cures underwater so a coat can even be put on prior to it going back in the water.

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13 minutes ago, Bloomsberry said:

My local chandlery only had one 2 pack epoxy in stock, interzone 954. Read up on it's performance and it was quite encouraging so decided to use it on my boat.

No need to worry about drying times with 954, it cures underwater so a coat can even be put on prior to it going back in the water.

Be very carful with that statement. It CAN be used on splash zones and for TIDAL immersion within 30mins of application but not full immersion. This coating contains 15% solvent and this has to come out before full cure is achieved. It will in a tidal situation where the coating will be exposed when the tide goes out. The solvent cannot get out if under water. Don't paint the bottom of a boat and put it straight back in the water. Let it fully cure first.

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13 hours ago, Troyg said:

Opinions certainly vary. At the moment I am leaning towards Hempel Hempadur 45143. I read that it is also surface tolerant. The drying times for the Jotamastic 87 put me off. The Sherwin Williams could be an option but doesn't seem that common? And which one to use? I assume the Macropoxy M922? Not much info for it if surface tolerant and resists oil etc.

Decisions to make but the 45143 is leading currently.....

I used that last year after the supplier said it's what the shipyards are using now. I added 3 coats instead of the normal 2.

To be honest Midnight was 2-packed from new. After 3 years I re-coated. After a further 4 years I found a lot of rusting and galvantic pitting around the waterline so have re-coated every 2 years since then. The problem with the 15130 was the toxic fumes. I used a gas mask but in an open-sided dry-dock. Although I used a similar mask for the 45143 there were no obvious strong fumes. That may mean it isn't as resilient as the 15130. Time will tell.

The supplier Carter Paints of Sunderland may be able to provide some feedback from the shipyards but at the end of the day it's all blacking no matter what you use and any 2-pack is probably more resilient that a single pack.

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27 minutes ago, Midnight said:

I used that last year after the supplier said it's what the shipyards are using now. I added 3 coats instead of the normal 2.

To be honest Midnight was 2-packed from new. After 3 years I re-coated. After a further 4 years I found a lot of rusting and galvantic pitting around the waterline so have re-coated every 2 years since then. The problem with the 15130 was the toxic fumes. I used a gas mask but in an open-sided dry-dock. Although I used a similar mask for the 45143 there were no obvious strong fumes. That may mean it isn't as resilient as the 15130. Time will tell.

The supplier Carter Paints of Sunderland may be able to provide some feedback from the shipyards but at the end of the day it's all blacking no matter what you use and any 2-pack is probably more resilient that a single pack.

2 pack epoxies should last far longer than 2-4 years on the hull of a NB. Your experience and need to recoat is most likely due to a lack of surface preparation or bad application. You really need to get back to clean steel and preferably SA 2 1/2  if you want it to last.....and apply the coating in line with the manufacturers instructions. If you cannot achieve this level of preparation, which is expensive, then it is a waste of time using a 2 pack and so a 'traditional blacking' single pack system is the best answer.

I do not understand your comment "but at the end of the day it's all blacking no matter what you use" . No it isnt. Prepare the surface very well and use a 2 pack epoxy for 10 years life or just water jet and slap on a bitumen based blacking and repeat every 2 years.

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1 hour ago, Dr Bob said:

Be very carful with that statement. It CAN be used on splash zones and for TIDAL immersion within 30mins of application but not full immersion. This coating contains 15% solvent and this has to come out before full cure is achieved. It will in a tidal situation where the coating will be exposed when the tide goes out. The solvent cannot get out if under water. Don't paint the bottom of a boat and put it straight back in the water. Let it fully cure first.

Ok, thanks for that.

 

It does say ' continued cure under immersed conditions' which I assumed would be full immersion but it does state tidal which obviously isn't relevant to my situation.

 

It states 18 hours for hard dry at 15C so will stick to this next time. Thanks again.

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