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DIY epoxy blacking.


rusty69

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3 minutes ago, Jon57 said:

The 3 disc is ok in a cheap drill, nice and light. Pack it off with some wood blocks and gaffer tape so the disc is just the right distance then you just have to keep going up and down (10000000000 times🤣)

The grit blasting or bitumen is beginning to sound like the preferable option. 

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I’m another who has 2 packed over bitumen 👍

Choose the correct 2 pack and prep like the others say and it should be ok. 
 

seems the expense and fuss of grit/sand blasting is a thing of the past. 
 

I’d add that if you’re doing a few coats then don’t leave too long a time between them. Over night is ok but a few days and the next coat doesn’t key to the surface quite so well. That was my experience. The 2 pack can cure quickly and give a smooth finish which the next layer won’t want to stick to. 
 

for any prep I just use a cup brush on angle grinder, light and easy to use, will take the loose off real quick and scratch up a good surface. 
I was able to get my hands on a needle gun which was great for doing along the welds of the rubbing strakes. 

Edited by Goliath
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1 minute ago, Goliath said:

I’m another who has 2 packed over bitumen 👍

Choose the correct 2 pack and prep like the others say and it should be ok. 
 

seems the expense and fuss of grit/sand blasting is a thing of the past. 
 

I’d add that if you’re doing a few coats then don’t leave too long a time between them. Over night is ok but a few days and the next coat doesn’t key to the surface quite so well. That was my experience. The 2 pack can cure quickly and give a smooth finish which the next layer won’t want to stick to. 
 

for any prep I just use a cup brush on angle grinder, light and easy to use, will take the loose off real quick and scratch up a good surface. 
I was able to get my handles on a needle gun which was great for doing along the welds of the rubbing strakes. 

Thank you. Which two pack did you go for, and have you seen the results since you applied it? 

Edited by rusty69
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A couple of thoughts. How old is the boat and has it been fairly frequently painted with bitumen? If the boat has been pulled out every few years, painted and is in good condition for its age I would be tempted to carry on with what you have been doing, maybe with a coating that is compatible with bitumen, Ballistic black maybe?  Epoxy is good but getting the old stuff off is a a sod and I really do not know how tolerant epoxy is to traces of bitumen. People say you cannot overcoat bitumen but you would need to ask, for instance, Jotun about that, they do a surface tolerant version and maybe a barrier/primer would work, I just do not know. Epoxy is expensive, more than one coat is really needed and risking it failing to stick is a worry. Also I think if you leave epoxy too long between coats the first coat will cure and the second coat might not stick well to it,  You might have to choose between grit blasting the thing and start again - expensive, or slap on a lot of bitumen and redo it every 3 years or so. Good luck.

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I’ll have a look at two pack and post the make when I find it. 
 

Boat came out the water about a month after painting. 
and all looked tickerty boo except for some patches where the layers of 2 pack didn’t adhere to each other as I described. 
 

from what I can see above the water line and at the waterline all looks good except for my scrapes,  

it’s been on since April last year
 

I won’t know for sure until the boat comes out again, that’s obviously the real test, but I’m pretty confident it’s all ok. 
 

it’s as hard as nails when it cures,

 

 



 

 

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31 minutes ago, rusty69 said:

Thanks. What is the polisher for? I was under the impression the Tercoo thing fits in a drill. 

 

Is it likely to loose teeth on contact with the rubbing bands? 

Polisher is the same as a big angle grinder except its a bit lighter (thank god) and with adjustable speed control you can run it at a decent speed. Comes with a handy handle too. 

I used one in a drill before and its alot slower although I was still impressed with it. Well must have been impressed enough to buy the mega expensive 7 disc and polisher one anyhow. Money well spent and done two hulls (50ft) with it and still got loads of life in it.

Not as good as getting someone else to do it though..

 

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9 minutes ago, Bee said:

A couple of thoughts. How old is the boat and has it been fairly frequently painted with bitumen? If the boat has been pulled out every few years, painted and is in good condition for its age I would be tempted to carry on with what you have been doing, maybe with a coating that is compatible with bitumen, Ballistic black maybe?  Epoxy is good but getting the old stuff off is a a sod and I really do not know how tolerant epoxy is to traces of bitumen. People say you cannot overcoat bitumen but you would need to ask, for instance, Jotun about that, they do a surface tolerant version and maybe a barrier/primer would work, I just do not know. Epoxy is expensive, more than one coat is really needed and risking it failing to stick is a worry. Also I think if you leave epoxy too long between coats the first coat will cure and the second coat might not stick well to it,  You might have to choose between grit blasting the thing and start again - expensive, or slap on a lot of bitumen and redo it every 3 years or so. Good luck.

The boat is an early 80s boat, with original 6mm plating. Its not in too bad condition at last survey, but does have some pitting. In our ownership we have used bitumen every 2-3 years for the last 24 years. 

 

At some point, it will likely require over plating. We are just trying to put off that date. 

 

Whether applying epoxy at this stage will make over plating in the future more difficult I don't know. 

6 minutes ago, PaulJ said:

Polisher is the same as a big angle grinder except its a bit lighter (thank god) and with adjustable speed control you can run it at a decent speed. Comes with a handy handle too. 

I used one in a drill before and its alot slower although I was still impressed with it. Well must have been impressed enough to buy the mega expensive 7 disc and polisher one anyhow. Money well spent and done two hulls (50ft) with it and still got loads of life in it.

Not as good as getting someone else to do it though..

 

I dare not ask how much the 7 blade version is. 

Edited by rusty69
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I think I used Jotumastic 87 last time, that was on top of a two pack Sigma Epoxy tar (now discontinued) It is supposed to be surface tolerant. I don't know how it has fared, the boat is due to come out this year. Goliath for one has used two pack over old coverings so that is helpful to know. I would reckon that some pitting is pretty reasonable for a boat from the early 80's and of course with new or active pits it seems that a covering of epoxy paint stops them dead so that's a Good Thing 

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1 minute ago, Bee said:

I think I used Jotumastic 87 last time, that was on top of a two pack Sigma Epoxy tar (now discontinued) It is supposed to be surface tolerant. I don't know how it has fared, the boat is due to come out this year. Goliath for one has used two pack over old coverings so that is helpful to know. I would reckon that some pitting is pretty reasonable for a boat from the early 80's and of course with new or active pits it seems that a covering of epoxy paint stops them dead so that's a Good Thing 

I've used jotmastic 87 before on our engine room, but of course, that didn't go over bitumen. 

 

The first two I mentioned in my OP, the glass flake stuff, I was advised could only go on if all the bitumen was removed. It was also a lot more expensive than the jotun and the ballastic stuff. 

 

It will be interesting to see how yours has faired. When is it out? 

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Apologies as you've probably seen this, but the Haggises used Northwich dry dock and apparently the high pressure washer is genuinely high pressure, and removes a lot of the crap from the surface. 

It wont get all the bitumen off you would imagine, but it might be a real help in terms of making the rest of the prep job easier?

I'd prefer to use them myself, but will the boat lift definitely be open?  

 

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36 minutes ago, rusty69 said:

Thank you. Which two pack did you go for, and have you seen the results since you applied it? 

  Ballistic Epoxy, which has been mentioned.

 

I had my boat on hard standing for a year.

In November ‘21 I gave the stern and the swim two good coats of International blacking.

I intended to black the rest of the hull with bitumen when the overplating was complete.

 

In March ‘22 I gave the base two coats of Hempel 2 pack, the base had never been painted.


When the welding and overplating was completed I was introduced to the Ballistic Expoxy.

I thought good idea on the new steel but what about the stuff I’d painted already?

I checked the specs and they reckoned it to be good for going over bitumen.

So in April the whole hull got two coating of Ballistic Expoxy.

The stern now has 4 coats; 2 bitumen and 2 epoxy.


So in short,  not only have I painted over tired and scratched patchy left over stubborn to remove bitumen on the bow, I repainted the stern which had a good surface of bitumen.

Time will tell, 

But it all seemed and still seems ok from what I can see.

 

 

 

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2 minutes ago, Tony1 said:

 

Apologies as you've probably seen this, but the Haggises used Northwich dry dock and apparently the high pressure washer is genuinely high pressure, and removes a lot of the crap from the surface. 

It wont get all the bitumen off you would imagine, but it might be a real help in terms of making the rest of the prep job easier?

I'd prefer to use them myself, but will the boat lift definitely be open?  

 

A high pressure washer is definitely a bonus. Unfortunately I am already booked in somewhere, and nowhere near Northwich. 

2 minutes ago, Goliath said:

  Ballistic Epoxy, which has been mentioned.

 

I had my boat on hard standing for a year.

In November ‘21 I gave the stern and the swim two good coats of International blacking.

I intended to black the rest of the hull with bitumen when the overplating was complete.

 

In March ‘22 I gave the base two coats of Hempel 2 pack, the base had never been painted.


When the welding and overplating was completed I was introduced to the Ballistic Expoxy.

I thought good idea on the new steel but what about the stuff I’d painted already?

I checked the specs and they reckoned it to be good for going over bitumen.

So in April the whole hull got two coating of Ballistic Expoxy.

The stern now has 4 coats; 2 bitumen and 2 epoxy.


So in short,  not only have I painted over tired and scratched patchy left over stubborn to remove bitumen on the bow, I repainted the stern which had a good surface of bitumen.

Time will tell, 

But it all seemed and still seems ok from what I can see.

 

 

 

Great thanks. The ballastic may be a good compromise for me if I can't get the prep upto spec in the given time. 

 

Obviously I'm not really going to know if 2 weeks is long enough until we get stuck in, but the correct tools and weather should get us a long way there. 

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10 minutes ago, rusty69 said:

A high pressure washer is definitely a bonus. Unfortunately I am already booked in somewhere, and nowhere near Northwich. 

Great thanks. The ballastic may be a good compromise for me if I can't get the prep upto spec in the given time. 

 

Obviously I'm not really going to know if 2 weeks is long enough until we get stuck in, but the correct tools and weather should get us a long way there. 

 

I think two weeks should be more than enough.

 

Yes of course Ballastic, I’ve said Ballistic.

 

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I have used a Sandvik 665 two handed scraper which takes 2" TC replacement blades to completely strip a hull. Removes any coating from the steel but it's hard work.

Applying 2 pack epoxy afterwards was successful, none peeled off in 20 years.

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3 minutes ago, Tracy D'arth said:

I have used a Sandvik 665 two handed scraper which takes 2" TC replacement blades to completely strip a hull. Removes any coating from the steel but it's hard work.

Applying 2 pack epoxy afterwards was successful, none peeled off in 20 years.

Thanks. Interesting option. Did you need to heat the surface first, or does it come off from cold?

 

I suppose any bitumen left in the pitting still has to be addressed. 

 

Could work well on a nice flat surface though. 

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24 minutes ago, rusty69 said:

Thanks. Interesting option. Did you need to heat the surface first, or does it come off from cold?

 

I suppose any bitumen left in the pitting still has to be addressed. 

 

Could work well on a nice flat surface though. 

The colder the better, the bitumen shatters off.  cover the pits or wire brush if big.

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I did my lumpy water boat with a 2" scraper. Much better for the lungs than a sander.  You need to knock the corners off the blade to stop them digging in, less immport on a steel boat, though they will cut through an epoxy coating. I needed to finnish off with a light sanding. A friend did his 57 ft narrowboat with a three disk Tesco, it seemed to take ages and ages, but the result was good enough for epoxy blacking.

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If you have a car or can hire transport, maybe you could hire out a grit blaster? 

 

This is one example, they hire a blaster for £100 per day, plus £7 for the gun and about a fiver for a 25kg bag of grit. 

One would imagine that after a good strong pressure wash, you could probably blast the hull clean in say 2 days? 

If you could, then for around £300 you could maybe do a half decent job of it yourself, and you'd certainly get into all the pits etc.

Also, it could be a lot less hard graft than some of the more manual scraping-type tools you might use. 

Its not the kind of thing you'd do at every blacking, but maybe once every 10 years to really get into the nooks and crannies etc.

 

https://www.evans-plant-hire.co.uk/plant-hire/sand-blasting/sand-blasting/

 

 

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Just now, Tony1 said:

 

If you have a car or can hire transport, maybe you could hire out a grit blaster? 

 

This is one example, they hire a blaster for £100 per day, plus £7 for the gun and about a fiver for a 25kg bag of grit. 

One would imagine that after a good strong pressure wash, you could probably blast the hull clean in say 2 days? 

If you could, then for around £300 you could maybe do a half decent job of it yourself, and you'd certainly get into all the pits etc.

Also, it could be a lot less hard graft than some of the more manual scraping-type tools you might use. 

Its not the kind of thing you'd do at every blacking, but maybe once every 10 years to really get into the nooks and crannies etc.

 

https://www.evans-plant-hire.co.uk/plant-hire/sand-blasting/sand-blasting/

 

 

Good idea Tony, but I wonder what the site owner would think of that, and the environmental implications? 

 

I'll take a look at the link. Cheers 

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5 minutes ago, rusty69 said:

Good idea Tony, but I wonder what the site owner would think of that, and the environmental implications? 

 

I'll take a look at the link. Cheers 

 

In a place where they do blasting themselves, they might be able to make arrangements to deal with the grit.

I'm considering changing and using Northwich dry dock myself this summer. They do blasting so will probably be more amenable to me doing it myself.

If there's a modest charge for them to remove the grit, then fair enough. Worth it, if it means a really good job. 

 

The charge for pro grit blasting seems a bit steep compared to the cost of hiring a DIY unit, hopefully that's not because they are really difficult to use properly.

Certainly worth a closer look though, and Evans are a national firm. 

 

 

Edited by Tony1
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5 minutes ago, rusty69 said:

Good idea Tony, but I wonder what the site owner would think of that, and the environmental implications? 

 

I'll take a look at the link. Cheers 

 

 

You could always end up doing a Michael Caine ......................

 

The attempt to blow the rust of the base plate, which caused its total destruction and produced Croker's other famous line "You're only supposed to blow the bloody rust off!", 

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There is a sort of nightmare scenario that has occurred to me- unlikely but possible- and that is I find significant pitting in some places. 

What measuring tools or techniques might one use to asses how serious any pitting is, if you see something you don't like the look of? 

 There wont be a lot of time to get a pro or surveyor involved as its all within a week or two at most, so it might be worth genning up on any likely methods of assessing how serious/deep pits are- kind of like a contingency plan. 

4 minutes ago, Alan de Enfield said:

 

 

You could always end up doing a Michael Caine ......................

 

The attempt to blow the rust of the base plate, which caused its total destruction and produced Croker's other famous line "You're only supposed to blow the bloody rust off!", 

 

I wont go near the doors! 

 

Also, I dont talk cockney me old sparrow.

 

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Just now, Tony1 said:

 

There is a sort of nightmare scenario that has occurred to me- unlikely but possible- and that is I find significant pitting in some places. 

What measuring tools or techniques might one use to asses how serious any pitting is, if you see something you don't like the look of? 

 There wont be a lot of time to get a pro or surveyor involved as its all within a week or two at most, so it might be worth genning up on any likely methods of assessing how serious/deep pits are- kind of like a contingency plan. 

 

 

There was a thread here some time ago where a boat yard had grit blasted a hull, not noticed they had 'gone thru', blacked the boat and put it back into the water and it sank overnight.

 

There was a big long ongoing discussion between insurance companies with the 'yard' saying they were asked to grit blast and black - not to ensure the boat was capable of having the work done.

 

The owner ended up selling it for 'scrap value'.

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