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DIY epoxy blacking.


rusty69

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I suppose with the power of hindsight, a good experiment would have been to get a lump of steel and do a side by side test on a submerged bit over a 3 year period. 

 

Obviously, it wouldn't tell the whole story, but might give an indication if its likely to just fall off in the space of a year. 

Edited by rusty69
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kelpie had been blacked with bitumen when we took it to Northwich where it was pressure washed and epoxied. After two years we booked into Northwich again and after the pressure washing the hull and base plate was still in good nick and we had it epoxied again. The reason for going back in just two years was because we, Like Ditchcrawler,  were not sure how well it would stick and also our mooring was between two liveaboards both connected to shore power and we wanted to make sure they were not affecting our hull.

All was well and we will leave it longer this time before we go back to Northwich to have her done again. 

 

haggis

 

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Just now, haggis said:

kelpie had been blacked with bitumen when we took it to Northwich where it was pressure washed and epoxied. After two years we booked into Northwich again and after the pressure washing the hull and base plate was still in good nick and we had it epoxied again. The reason for going back in just two years was because we, Like Ditchcrawler,  were not sure how well it would stick and also our mooring was between two liveaboards both connected to shore power and we wanted to make sure they were not affecting our hull.

All was well and we will leave it longer this time before we go back to Northwich to have her done again. 

 

haggis

 

That's encouraging. Thanks. 

1 minute ago, haggis said:

kelpie had been blacked with bitumen when we took it to Northwich where it was pressure washed and epoxied. After two years we booked into Northwich again and after the pressure washing the hull and base plate was still in good nick and we had it epoxied again. The reason for going back in just two years was because we, Like Ditchcrawler,  were not sure how well it would stick and also our mooring was between two liveaboards both connected to shore power and we wanted to make sure they were not affecting our hull.

All was well and we will leave it longer this time before we go back to Northwich to have her done again. 

 

haggis

 

Do you recall what epoxy was used and how many coats? 

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24 minutes ago, rusty69 said:

That's encouraging. Thanks. 

Do you recall what epoxy was used and how many coats? 

The invoices are on the boat and we are at home so don't know what epoxy was used. However, chatting with himself we think 3 coats went on. Into dry dock on Saturday morning and pressure washed (by Matt) in the afternoon. Sides and base plate. We are sure a coat was put on on Sunday, Monday and Tuesday leaving Wednesday to Saturday morning for it to completely dry before we left the dry dock . I had planned to paint the bit between the gunwale and rubbing strake with epiphany (i think that's the name) but with the boat being up on blocks, I couldn't reach and I am not good up ladders :-). We got the painter who works beside the dry dock to do it (using our paint). Kelpie looked lovely after all the titivating. 

We and the dog lived on board in the dry dock which is the cleanest dry dock I have ever seen! 

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4 minutes ago, haggis said:

The invoices are on the boat and we are at home so don't know what epoxy was used. However, chatting with himself we think 3 coats went on. Into dry dock on Saturday morning and pressure washed (by Matt) in the afternoon. Sides and base plate. We are sure a coat was put on on Sunday, Monday and Tuesday leaving Wednesday to Saturday morning for it to completely dry before we left the dry dock . I had planned to paint the bit between the gunwale and rubbing strake with epiphany (i think that's the name) but with the boat being up on blocks, I couldn't reach and I am not good up ladders :-). We got the painter who works beside the dry dock to do it (using our paint). Kelpie looked lovely after all the titivating. 

We and the dog lived on board in the dry dock which is the cleanest dry dock I have ever seen! 

Thanks. 

 

Epifanes? 

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1 hour ago, haggis said:

The invoices are on the boat and we are at home so don't know what epoxy was used. However, chatting with himself we think 3 coats went on. Into dry dock on Saturday morning and pressure washed (by Matt) in the afternoon. Sides and base plate. We are sure a coat was put on on Sunday, Monday and Tuesday leaving Wednesday to Saturday morning for it to completely dry before we left the dry dock . I had planned to paint the bit between the gunwale and rubbing strake with epiphany (i think that's the name) but with the boat being up on blocks, I couldn't reach and I am not good up ladders :-). We got the painter who works beside the dry dock to do it (using our paint). Kelpie looked lovely after all the titivating. 

We and the dog lived on board in the dry dock which is the cleanest dry dock I have ever seen! 

I think we had two coats with airless spray

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20 hours ago, rusty69 said:

Will do. The place I  going has something called a hydroblaster, so I might try that. I'm yet to talk to the chap who operates it for his opinion. 

 

I get the impression it's a pressure washer with the ability to add some kind of sand in with the mix. 

 

Clive's hydroblaster will take off all the existing bitumen. It's just very high pressure water - there's no ability to add sand or grit. He struggled to get all my 7 year old epoxy off with the hydroblaster so he switched to grit blasting but for getting off bitumen it will be fine. Some may have had success painting epoxy over bitumen but it's not recommended practice. No epoxy manufacturer or paint supplier I know of recommend doing that in their application guides. 

 

After the hydroblasting I'd try to give the whole hull a key before applying epoxy if you can. The problem with Blackthorn is that it's very weather dependent as you're not under cover.

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Just now, blackrose said:

 

Clive's hydroblaster will take off all the existing bitumen. It's just very high pressure water - there's no ability to add sand or grit. He struggled to get all my 7 year old epoxy off with the hydroblaster so he switched to grit blasting but for getting off bitumen it will be fine. Some may have had success painting epoxy over bitumen but it's not recommended practice. No epoxy manufacturer or paint supplier I know of recommend doing that in their application guides. 

 

After the hydroblasting I'd try to give the whole hull a key before applying epoxy if you can. The problem with Blackthorn is that it's very weather dependent as you're not under cover.

That's good to know.  I didn't think the hydroblasting thing would be good enough for that.

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4 minutes ago, blackrose said:

 

Clive's hydroblaster will take off all the existing bitumen. It's just very high pressure water - there's no ability to add sand or grit. He struggled to get all my 7 year old epoxy off with the hydroblaster so he switched to grit blasting but for getting off bitumen it will be fine. Some may have had success painting epoxy over bitumen but it's not recommended practice. No epoxy manufacturer or paint supplier I know of recommend doing that in their application guides. 

 

After the hydroblasting I'd try to give the whole hull a key before applying epoxy if you can. The problem with Blackthorn is that it's very weather dependent as you're not under cover.

Do you reckon hydroblasting and wire brushing with a cup brush in an angle grinder will be sufficient for jotun epoxy (not sure if 87 or 90)?

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4 hours ago, rusty69 said:

I suppose with the power of hindsight, a good experiment would have been to get a lump of steel and do a side by side test on a submerged bit over a 3 year period. 

 

Obviously, it wouldn't tell the whole story, but might give an indication if its likely to just fall off in the space of a year. 


I think if it hasn’t fell off in the space of a few weeks or months it should be ok. 
 

I really couldn’t understand wanting to blast off good hardened blacking that had layered in places over the years, doing exactly what’s wanted. 
 

If the epoxy adheres which it looks like it has then 👍

 

I hope I can afford to take the boat out this year to have a look. 
Ive gone to an extreme in the experiment but we’ll see. 

At the end of the day whatever paint used a concrete edging, metal rails or ice will scrap it off. 
I’ve had a couple of days driving through ice and it has took it’s toll. 
 

Hopefully any epoxy stays in the pits and dints. 🤞
 

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5 minutes ago, Goliath said:


I think if it hasn’t fell off in the space of a few weeks or months it should be ok. 
 

I really couldn’t understand wanting to blast off good hardened blacking that had layered in places over the years, doing exactly what’s wanted. 
 

If the epoxy adheres which it looks like it has then 👍

 

I hope I can afford to take the boat out this year to have a look. 
Ive gone to an extreme in the experiment but we’ll see. 

At the end of the day whatever paint used a concrete edging, metal rails or ice will scrap it off. 
I’ve had a couple of days driving through ice and it has took it’s toll. 
 

Hopefully any epoxy stays in the pits and dints. 🤞
 

I can see your point, and agree that removing good hull protection for no reason is pointless, and hard work IF the epoxy adheres to it. However, I am far from certain that it does long term.

 

Even if it doesn't, and lasts the same time as bitumen, there is an added cost to using epoxy, but given the choice, I reckon following the paint manufacturers instructions is always the best option if you can.

 

I haven't actually read the instructions for the ballastic stuff yet, but understand that it is marketed such that it can be applied on top of existing bitumen. The chemco glass flake epoxy, and the Sherwin Williams epoxy both say that all traces of bitumen must be removed prior to application.

 

I've not looked into the Jotun 87 and 90 yet,and don't know the difference between them, but I suspect they will say the same.

 

What the difference is between the ballastic one that requires all the bitumen be removed and the ones that don't, I'm far from certain.

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1 hour ago, rusty69 said:

Do you reckon hydroblasting and wire brushing with a cup brush in an angle grinder will be sufficient for jotun epoxy (not sure if 87 or 90)?

 

You've just got to be careful that the wire brush isn't polishing rather than keying. Clive has a massive angle grinder with a huge sanding disc that he might lend you if you ask nicely. If you're gentle you could give the steel a key without removing good steel. Or just do the same with a mini angle grinder as you'll probably have more control. A coarse flap wheel disc will do it but you'll have to be gentle. You don't want to remove good steel.

Edited by blackrose
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1 minute ago, rusty69 said:

I can see your point, and agree that removing good hull protection for no reason is pointless, and hard work IF the epoxy adheres to it. However, I am far from certain that it does long term.

 

Even if it doesn't, and lasts the same time as bitumen, there is an added cost to using epoxy, but given the choice, I reckon following the paint manufacturers instructions is always the best option if you can.

 

I haven't actually read the instructions for the ballastic stuff yet, but understand that it is marketed such that it can be applied on top of existing bitumen. The chemco glass flake epoxy, and the Sherwin Williams epoxy both say that all traces of bitumen must be removed prior to application.

 

I've not looked into the Jotun 87 and 90 yet,and don't know the difference between them, but I suspect they will say the same.

 

What the difference is between the ballastic one that requires all the bitumen be removed and the ones that don't, I'm far from certain.

Absolutely, it’s your call and I wouldn’t want to tell anyone how to do a job 👍

 

 

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Just now, Goliath said:

Absolutely, it’s your call and I wouldn’t want to tell anyone how to do a job 👍

 

 

I'm grateful for all input. As I say, I've never done this before, so its all a bit daunting.

 

If I can, I will go the jotun route with the hydroblaster thing if I can get it clean enough.

 

If I can't, I will likely opt for the ballastic stuff, concentrating on the area around and below the waterline.

 

 

 

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1 hour ago, blackrose said:

 

Clive's hydroblaster will take off all the existing bitumen. It's just very high pressure water - there's no ability to add sand or grit. He struggled to get all my 7 year old epoxy off with the hydroblaster so he switched to grit blasting but for getting off bitumen it will be fine. Some may have had success painting epoxy over bitumen but it's not recommended practice. No epoxy manufacturer or paint supplier I know of recommend doing that in their application guides. 

 

 

I know that Matt at Northwich looked very closely into what can be applied on top of what and spoke to manufacturers and I think it highly unlikely that he would be doing it if it was "not recommended practice".  After all if it wasn't working his business would be at risk and he wouldn't be having so many returning customers.

To me it seems a waste to get rid of something which has worked well for years and grit blasting must be one of the nastiest dirtiest jobs around :-),

 

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37 minutes ago, haggis said:

I know that Matt at Northwich looked very closely into what can be applied on top of what and spoke to manufacturers and I think it highly unlikely that he would be doing it if it was "not recommended practice".  After all if it wasn't working his business would be at risk and he wouldn't be having so many returning customers.

To me it seems a waste to get rid of something which has worked well for years and grit blasting must be one of the nastiest dirtiest jobs around :-),

 

It certainly seems to me that not all epoxy is born equal. The chemco glass flake epoxy, and the Sherwin Williams epoxy definitely require all bitumen to be removed, as I contacted both.

 

Whereas your epifanes and the ballastic stuff suggest that it is ok. I wonder if the answers lie within the data sheets, or perhaps the marketing department?

Edited by rusty69
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Ballastic Epoxy 5L

This advanced product bridges the gap between having to sand, or blast back, a steel canal boat to bare metal before applying a two-pack epoxy primer, for a 10 year paint system and having to apply a bitumen-based product every year or so. Ballastic Epoxy is a two-pack primer but it can be applied over existing bitumen paint and has all the protection of an epoxy primer which will allow the use of better quality two-pack topcoats.

When mixed the two components make 5 litres of paint.

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So, trawling though previous threads, I found this comment from @Dr Bob Trust him. He's a dogtor. Anyone got a data sheet for the epifanes or ballastic?

 

Ok, found the datasheet for the ballastic stuff, but still non the wiser.

 

Quote

There are 2 types of coatings. Barrier and passive. Epoxies are barrier. They work by stopping water and oxygen getting to the surface BUT they must have excellent adhesion to the substrate ( i.e. Steel). That stops undercutting and rust penetration under the coating. They will not work well if applied over a soft single pack with poor adhesion i.e. Blacking.

Now if the OP has found some super duper snake oil type modified epoxy that will work as a barrier over soft coatings then let's see the data sheets. In 40 years since being in the epoxy formulation game, none of the big boys have EVER achieved this!

Trust me, I'm a doctor.

Thread here:

 

Ballastic epoxy data.pdf

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30 minutes ago, rusty69 said:

It certainly seems to me that not all epoxy is born equal. The chemco glass flake epoxy, and the Sherwin Williams epoxy definitely require all bitumen to be removed, as I contacted both.

 

Whereas your epifanes and the ballastic stuff suggest that it is ok. I wonder if the answers lie within the data sheets?

I am fairly sure Epifany paint is NOT the same as blacking. We use it on the bit between the rubbing strake and the gunwale ie the bit above the water line. The previous owner of the boat used it and left some on board so we continued using it and it does the job of keeping that bit looking good and as it is easy to apply.  Sorry if I gave the impression that it was a form of bottom blacking 

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1 minute ago, haggis said:

I am fairly sure Epifany paint is NOT the same as blacking. We use it on the bit between the rubbing strake and the gunwale ie the bit above the water line. The previous owner of the boat used it and left some on board so we continued using it and it does the job of keeping that bit looking good and as it is easy to apply.  Sorry if I gave the impression that it was a form of bottom blacking 

Ah, ok. Apologies,I was getting that mixed up with what you used below the waterline.

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