Jump to content

Epoxy primer on top of bitumen?...


Tom Clegg

Featured Posts

7 minutes ago, Tom Clegg said:

Hello all,

 

Does anyone have any thoughts on or experience of using this product?

 

https://www.smlmarinepaints.co.uk/primers/two-pack/Ballastic_Epoxy

 

A new product apparently, which allows epoxy to be painted over existing bitumen.

 

Many thanks,

 

Tom

AFAIK the main reason for using epoxy is to get an "inter-molecular bond" with the steel which won't happen unless you have clean steel (normally Sa2.5 standard), but I may be way off the mark.

Link to comment
Share on other sites

It may well stick to, and work over bitumen.  It cannot change the bond between the bitumen and the steel so that is what your (expensive?) new epoxy paint job will be relying on.

 Bitumen can be made to stick to steel well, but that involves the sort of preparation that epoxy would need. Bitumen rolled over mill scale in the usual way is very easily mechanically damaged by every day boating.  Putting epoxy on top ain't going to change that.  You would also need to ensure the epoxy layer was completely watertight over the bitumen or the water and diesel/oil on the water will get behind the epoxy and wreak coating havoc, albeit slowly.

N

Link to comment
Share on other sites

I might try it, as I think someone has put some bitumen on the boat after some work done at the stern, I think the boat has had two pack epoxy from new, not sure if it was ever over coated, it's 18 years old, but hull was super clean, though it was supposed to get a new coating before launch, that never happened. 

I would wire brush and scrape in order to remove as much bitumen as posible

I less than impressed with the name, if its a primer, that should be in the name, not the small print, imho. 

Problem is that I real only need one litre. I suppose I could coat the upper part of the Hull where its not exposed to immersion, and put two coats of standard epoxy on at the waterline. One can never be sure what shade of grey it will end up. 

 

 

Edited by LadyG
Link to comment
Share on other sites

27 minutes ago, BEngo said:

It may well stick to, and work over bitumen.  It cannot change the bond between the bitumen and the steel so that is what your (expensive?) new epoxy paint job will be relying on.

 Bitumen can be made to stick to steel well, but that involves the sort of preparation that epoxy would need. Bitumen rolled over mill scale in the usual way is very easily mechanically damaged by every day boating.  Putting epoxy on top ain't going to change that.  You would also need to ensure the epoxy layer was completely watertight over the bitumen or the water and diesel/oil on the water will get behind the epoxy and wreak coating havoc, albeit slowly.

N

This is very helpful, thank you!

Link to comment
Share on other sites

I think the answer is that this could well be snake oil. Thing is nobody on here can tell you for sure whether this will work or not. The company MUST be able to provide irrefutable proof that it will be worth  you spending the money on their product. Bottom line is that bitumin lasts, at best, for 2 years. Diesel in the water will very quickly melt bitumin and that same diesel in the water can also get under bitumin, especially where the bitumin has been scraped off, and weaken what is already a fairly weak bond of the bitumin to the steel after all bitumin is a fairly viscous substance compared to most paints even after application, ie it can be scraped off with a fingernail even after being on for a couple of years. I think the peole to ask some very searching questions are the manufacturers of this wonderous substance.

Link to comment
Share on other sites

A couple of years ago I had my boat done like this at Northwich Dry Dock. I was very much in 2 minds about it and still am. I will let you know how well it worked when its next docked. I don't think standard blacking works that well regardless of how well its applied so whether this will be any better I will tell you next time its done.

http://www.northwichdrydock.com/services/hull-blacking-service/

 

Link to comment
Share on other sites

  • 2 months later...

Has anybody got an update on this. I've used keelblack successfully the last 2 times. It's harder and thinner than conventional blacking, far less prone to flaking when scraped. Due to go in dock soon for survey and blacking. 

Link to comment
Share on other sites

On 01/02/2021 at 12:21, ditchcrawler said:

A couple of years ago I had my boat done like this at Northwich Dry Dock. I was very much in 2 minds about it and still am. I will let you know how well it worked when its next docked. I don't think standard blacking works that well regardless of how well its applied so whether this will be any better I will tell you next time its done.

http://www.northwichdrydock.com/services/hull-blacking-service/

 

I am considering having my boat 2 packed there. They seem really helpful there. The word is they have the mother of all pressure washers instead of a back to metal approach. If the pressure doesn't take off the bitumen remaining bitumen can take 2 pack? Bare metal and bitumen combination. Less mess and cost? 

Link to comment
Share on other sites

14 minutes ago, Hartlebury lad said:

I am considering having my boat 2 packed there. They seem really helpful there. The word is they have the mother of all pressure washers instead of a back to metal approach. If the pressure doesn't take off the bitumen remaining bitumen can take 2 pack? Bare metal and bitumen combination. Less mess and cost? 

I will let you know next year

Link to comment
Share on other sites

Lots of good information. Epoxy will stick to anything, hair, glasses, dogs, underpants - I used some red epoxy on Bee the docking before last and e big thumbprint is still on the waistband of an old pair in the back of the pants draw - Yeah, I know, nobody wanted to know that. This stuff sounds like a bituminous based paint but with epoxy chemicals and hardner so it is probably a improved version of bituminous paint, better than ordinary black stuff but maybe not as good as proper epoxy - sort of like coal tar epoxy which is banned abroad, don't know about the UK

Link to comment
Share on other sites

14 minutes ago, Bee said:

Lots of good information. Epoxy will stick to anything,

 

The 2-pack epoxy I used made sure that you were aware of its limitations in BIG BOLD type It is highlighted that the problem is when overpainting is the chemical reaction with the previous paint. You can overpaint 2-pack with 'ordinary' paint, but not the other way around.

 

I had left a small patch of paint after stripping back and after 2-pack it 'boiled and blistered' as it reacted with the old paint. I had to scrape it all off remove the remains of the old paint before priming and re-painting with 2-pack

Link to comment
Share on other sites

Always useful to remember that whilst one coat of paint may stick to the previous layer, that older layer may not stick to anything - including the hull. Chemical reactions may make the situation worse if it reduces the adhesion between the older layer  and what is underneath it.

Link to comment
Share on other sites

1 hour ago, Mike Todd said:

Always useful to remember that whilst one coat of paint may stick to the previous layer, that older layer may not stick to anything - including the hull. 

If the bottom layer is not stuck whatever you put on top is going to fail so that's true with standard blacking as well.  I didn't see any sign of a chemical reaction but we will find out when its next docked. Even though I had it done I am still sceptical but hole I made the right decision.

Link to comment
Share on other sites

On 03/04/2021 at 21:08, Jim Riley said:

Has anybody got an update on this. I've used keelblack successfully the last 2 times. It's harder and thinner than conventional blacking, far less prone to flaking when scraped. Due to go in dock soon for survey and blacking. 

Hi Jim this is one of the very few reports of successful use of Keelblack I've heard. Several boat club members tried it without success so they are now using the Ballistic 2-pack. Too early to report back I'm afraid. As the club has it's own Dry Dock we tend to go in annually or every 2 years max. I have my doubts about 2-pack without sand-blasting but TBH using any 2-pack on top of bitumen must be better than or at least equal to using just normal blacking.

Link to comment
Share on other sites

1 hour ago, Midnight said:

  TBH using any 2-pack on top of bitumen must be better than or at least equal to using just normal blacking.

That was my view in the end, I know standard black doesn't work that well with oil etc on the water.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.