Epoxy Blacking

[BobsDadBod]

This is my first time DIY blacking my 55ft narrow boat. I'd previously had bitumen based blacking applied (much longer ago than should have been). After plenty of research I found a SML 2pack that boats the ability to go over bitumen. (https://www.smlmarinepaints.co.uk/primers/two-pack/Ballastic_Epoxy)

Have prepped and blacked. 3 coats from just above water line to base plate, 2 coats above water line to gunwale. I have an entire unused tin that's sealed and as new, just wondering whether additional coats of 2-pack is beneficial to longevity of the blacking or to try and return/sell the unused can. 

 

I'm not bothered about chalking and will not be covering with a top coat - I do plan on jet washing the base plate and applying standard bitumen to the baseplate - though I understand there's mixed opinions on this. 
 

 

[Barneyp]

4 minutes ago, BobsDadBod said:

This is my first time DIY blacking my 55ft narrow boat. I'd previously had bitumen based blacking applied (much longer ago than should have been). After plenty of research I found a SML 2pack that boats the ability to go over bitumen. (https://www.smlmarinepaints.co.uk/primers/two-pack/Ballastic_Epoxy)

Have prepped and blacked. 3 coats from just above water line to base plate, 2 coats above water line to gunwale. I have an entire unused tin that's sealed and as new, just wondering whether additional coats of 2-pack is beneficial to longevity of the blacking or to try and return/sell the unused can. 

 

I'm not bothered about chalking and will not be covering with a top coat - I do plan on jet washing the base plate and applying standard bitumen to the baseplate - though I understand there's mixed opinions on this. 
 

 

My first question is why have you got a full tin left over - did you buy to much, or have you applied it to thinly?

 

It shouldn't be that hard to calculate the approximate area you have coated, and then from the manufacturers instructions/data on coverage work out how much you should of used.

 

If the coatings you have put on are to thin there is definitely value in another coat.

If you think that you have coated to the correct thickness, then additional coatings are governed by the law of diminishing returns, each additional coat will provide less protection, and there are negative effects of having the paint to thick - more likely to chip or flake off if damaged, less able to cope with the steel expanding/contracting due to temperature changes.

 

Whats the expiry date on the tin, could you keep it for repairing damaged areas in a couple of years time.

 

 

 

 

[Tracy D'arth]

Use the spare tin on the baseplate, it will last much better than bitumen.

[ditchcrawler]

3 hours ago, Tracy D'arth said:

Use the spare tin on the baseplate, it will last much better than bitumen.

Someone will be along shortly to tell you the base plate doesn't need painting

[BobsDadBod]

21 hours ago, Barneyp said:

My first question is why have you got a full tin left over - did you buy to much, or have you applied it to thinly?

 

Whats the expiry date on the tin, could you keep it for repairing damaged areas in a couple of years time.

 

 

 

 

 

I purchased through the website as a '65ft narrow boat blacking kit' because the 50ft wouldn't have had enough, so I was expecting some left over anyway. I made up and mixed small amounts as I was going. Confident the water line and below has plenty thick enough coats on at least for the initially. I'd struggle to say for 2nd and 3rd coat as painting black on black. I don't feel like I was stingy with the epoxy and every where was coated. 

Expiry is 2 yrs. 

 

21 hours ago, Tracy D'arth said:

Use the spare tin on the baseplate, it will last much better than bitumen.

I considered this but wasn't sure I'd be able to prepare to the necessary standard, I'll be able to jet wash, but am unable to get under to fully sand down to bare steel. Do you think would still be worthwhile using even if just roughly prepared? 

[LadyG]

13 minutes ago, BobsDadBod said:

 

I purchased through the website as a '65ft narrow boat blacking kit' because the 50ft wouldn't have had enough, so I was expecting some left over anyway. I made up and mixed small amounts as I was going. Confident the water line and below has plenty thick enough coats on at least for the initially. I'd struggle to say for 2nd and 3rd coat as painting black on black. I don't feel like I was stingy with the epoxy and every where was coated. 

Expiry is 2 yrs. 

 

I considered this but wasn't sure I'd be able to prepare to the necessary standard, I'll be able to jet wash, but am unable to get under to fully sand down to bare steel. Do you think would still be worthwhile using even if just roughly prepared? 

Yes, I don't think standard bitumen blacking has any better characteristics.

Just prep it best you can and you should have enough for two coats, make sure the edge gets a good finish . I would avoid using steel wire brushes but I think a brass cupped brush on a power drill, and a lightweight sander plus lots of paper from very coarse to medium would work.

It won't be perfect and it won't be easy.

Good personal protection required. 

 

 

Edited September 24, 2022 by LadyG

[matty40s]

34 minutes ago, LadyG said:

Yes, I don't think standard bitumen blacking has any better characteristics.

Just prep it best you can and you should have enough for two coats, make sure the edge gets a good finish . I would avoid using steel wire brushes but I think a brass cupped brush on a power drill, and a lightweight sander plus lots of paper from very coarse to medium would work.

It won't be perfect and it won't be easy.

Good personal protection required. 

 

 

The answer is NO.

 

Do you ever read what someone says, or just make it up as you think??

 

I'll be able to jet wash, but am unable to get under to fully sand down to bare steel. Do you think would still be worthwhile using even if just roughly prepared

[Tracy D'arth]

1 hour ago, BobsDadBod said:

 

I purchased through the website as a '65ft narrow boat blacking kit' because the 50ft wouldn't have had enough, so I was expecting some left over anyway. I made up and mixed small amounts as I was going. Confident the water line and below has plenty thick enough coats on at least for the initially. I'd struggle to say for 2nd and 3rd coat as painting black on black. I don't feel like I was stingy with the epoxy and every where was coated. 

Expiry is 2 yrs. 

 

I considered this but wasn't sure I'd be able to prepare to the necessary standard, I'll be able to jet wash, but am unable to get under to fully sand down to bare steel. Do you think would still be worthwhile using even if just roughly prepared? 

Grit blast is the right way, can you get a portable blasting guy in?  Otherwise you are in for a right long slog to clean back a baseplate.

 

Whatever you do, it will be better on the boat than in a tin!

[LadyG]

3 hours ago, matty40s said:

The answer is NO.

 

Do you ever read what someone says, or just make it up as you think??

 

I'll be able to jet wash, but am unable to get under to fully sand down to bare steel. Do you think would still be worthwhile using even if just roughly prepared

I read wot he said: he can't get the job done properly, so it's a compromise, his Q was about using the last tin of Ballistic rather than buying a tin of bitumen blacking.

He will be able to do something to prep it, if he can get the base power washed he has access to power. So he can do a bit of prepping.

See above post.

Edited September 24, 2022 by LadyG