barmyfluid

The benefit of opt 2 (as I see it) is that it's going to be better than bitumen for the 2(ish) years with regard to diesel spills. 2ish years is also when you should be checking your prop, anodes & hull anyway, it's not like you can say, 'right, that's it for 10 years...' and not bother hauling out. Cons - expensive innit. Seriously though, I'm well impressed with Vinyguard, which definitely IS meant to be used over bitumen.

I can't quite recall why I didn't, though when I arrived at the boatyard the first thing they offered me was to black her using epoxy over my bitumen (after a scrape and pressure wash), saying that's what they did as standard now. There are 2 things being talked about here. 1: The correct application of epoxy to a bare metal surface, giving maximum adhesion and longevity, up to 10 years. Following the instructions to the letter. There is no shortcut to this, and no snake oil solution. Dr Bob is right. 2: Scraping and washing loose bitumen off then applying epoxy. Repeat every 2 years. What comes off, comes off, and you're gradually getting better adhesion. But it's totally not scenario 1.

His reply really did ignore the details of what was being talked about, that the epoxy goes on a well prepared (but not totally bitumen free) surface, and that it wasn't meant to be the '10 year' job a traditional application of epoxy is rated for - it was in fact part of a more regular application that progressively improved. He's not wrong, but also not really on target. However - I didn't end up using it, so can't report! What I DID end up using was Jotun Vinyguard as an 18" stripe at the waterline with tradition bitumen over the top. It's solvent based and melted into the existing bitch after a scrape/wash. 2 year report on that - brilliant stuff. The bitumen, as expected, had softened up a lot from diesel spills, and I had a forced ice cruise just before Christmas that stripped a lot off. The Vinyguard is completely intact, and a big improvement on just bitumen. Really no rust at all other than some gouges on rubbing strakes etc.

SML Vinyguard and Ballastic epoxy for a couple: https://www.smlmarinepaints.co.uk/files/library/files/DATA_SHEETS/Vinyguard_Silvergrey_88_AG.pdf I've never seen it as a requirement for standard blacking either, though I'd guess it's not immune. I would be wary of high pH or chemical runoff, that's why I thought soda crystals may be a good choice, they're pretty innocuous in the scheme of things, they're used in laundry etc.

A few hull coating data sheets I've seen recently specify an alkaline degreaser as part of the prep. What are people using? I was thinking of plain soda crystals in hot water, safe and cheap, pH of around 11, would that do the job?

Hah, just mentioned that - yes, definitely. I'd often wondered if there wouldn't be some sort of sealant that would work to some degree over bitumen to give it solvent resistance at the waterline, something like a spray varnish. I'm sure I've heard people say that a 'paint job' is as good or better than blacking, and I've seen some odd looking waterlines going by from time to time.

I was planning on cup brushing the waterline at least, I think that's the main area where it stands a chance of being worth the extra cost over standard. I had rust spots with bitumen (Hempel) within 8 months previously, I'll certainly report back, many people are interested.

Oooh I don't know, was down the Nile the other day, got chafed by a crocodile, t-boned by a hire dhow and rammed a block of pyramid stone that was on the bank.

Thank you for your opinion and input, it's appreciated. Not sure what I'm not listening to Blackrose about as they said "If I still had bitumen on my hull I'd probably give this stuff a go", the rest appears to be repeated questions about usage I'd already answered until it got a bit sniffy. I've also, repeatedly, said I think it probably wouldn't be as good as a shotblast job but be a bit better than bitumen, I don't see why you think I'm not listening or disagreeing with consensus, or what you just said. Well, I do, because I know that nobody actually bothers reading posts, they just scan for word combinations that make them angry then fire off. Honestly, the internet.....

Lol, funny how 'watching paint dry' a simile for boring but suggesting a new product is grounds for rage and cries of heresy. When she could no longer hide him, she took a papyrus basket for him, and coated it with tar and with pitch. She put the child in it, and laid it in the reeds by the river's bank Exodus 2 Oh, it was good in the time of Moses, it's good enough for me.........

As I mentioned several times in this thread, it was unclear on the datasheet (which is letterheaded as SML, so that's as close to the horses mouth as I can find, if you know better, please share) as to what it's supposed to go under. It's vague at best. So I emailed SML for further information, and (again, as I've mentioned several times), they informed me that it is in fact fine as a single coating, or can be overcoated with other epoxies, such as Jotun topcoats. I don't understand your problem. I've listened to everyone on this thread, and agree with most, I'm certainly dubious about a new product that aims to sidestep a big cost ('"sounds too good to be true"), but I've explained why I think (or hope) it may be ok and worth a punt.

By itself the product is a 2 pack epoxy coating, it's called 'Ballastic epoxy' and it's implied you understand what this is; as I said, I had to email SML before finding out using it on it's own was fine, that is 'the upgrade'. If you want it from the horses mouth or are unsure of something, email SML.

Dunno who makes it, and it's not very clear about use for NB blacking TBH, I exchanged a few emails with SML before I found out. Although it's billed as an undercoat, a topcoat is only essential to stop it chalking, and for below waterline use you can use it on its own, and they recommended 'at least 2 good coats', so I was planning 2 and another at the waterline. It doesn't have to be perfect or as good as a shotblast job, it just needs to be better than bitumen, and at the waterline that's next to useless after a few slicks, ice etc. Upgrading from bitumen etc to an epoxy based one.

They're the main UK distributer for Jotun and are saying it's suitable for topcoating with Jotun etc, so I'm presuming they're fairly confident about its performance, it'd be very bad for a reputable company to tout a crap product that's going to cause loads of bad press down the line. Or one would presume so. New and game changing products do get invented, we'd all be cruising in reed coracles if they didn't.

As in a different type of epoxy with different characteristics. I'm just quoting SML. It's linked on the OP, scroll down the product page. Data sheets on the product page linked on the OP.

It's not at all compatible, which was why I '!?' the idea on the OP. As I said, I think the idea of J87 over anything but shotblasted steel is a dead end and a crossed wire with the yard. HOWEVER - Ballastic Epoxy is touted by SML as to be able to be top coated with further epoxy coating. It's actually down as a primer suitable to go over bitumen, though they told me a topcoat was optional and it's fine on its own as blacking. What a time to be alive.

I get surrounded by fuel spills all the time - most are from bilge pumps and leaky engines. Well, the product I'm planning on using is specifically for use over 'aged' existing coatings, bitumen being one. The recommended prep is pressure washing, degreasing and giving any gloss a key with sanding. At the end of this, whatever is left on there will have a reasonable amount of adhesion, and one of the features of the new epoxy is a level of flexibility, which I guess gives it more of a sheathing quality and prevents 'chunks' of it and whatever is beneath being knocked off. We paint over primer all the time - so long as it's stuck, and the paint is formulated to stick to that....But as I said, I don't think any coating will stand up to being bashed about between hull and locks for long. Given the cost saving of not having to shot blast, it seems worth a try at least.

Yeah, I think there were crossed wires with the yard on this one but it was worth asking about. I'm also hoping SML know what they're talking about with Ballastic Epoxy, as it's such a new product it's hard to find real world reports on performance. Being such a big hitter in the marine coatings world you'd think they wouldn't put out something that performed poorly when used as recommended.

Was it just 'standard' 2 pack then, as that's what the yard said they used over bitumen? Do you think it's performed better or worse than straight bitumen at the waterline?

Cheers for the report. I think if the waterline looks ok after a year it's a good sign, and the resistance to fuel has got to be worth the cost, even if overall it's not as tough as a shotblast job. TBH I think any coating + prep will lose the argument between a 15 ton boat and approaching bridge hole.

Not having it trashed by the first fuel spill I go through?

Well, the instructions with the newer stuff are loud and clear that it's allegedly fine over a variety of coatings so long as they're well prepared, but AFAIK Jotun 87 is bare metal only going by the book. However, I've learned that by the book doesn't always reflect on reality, especially in the marine world.

I'd decided to give SML's new ballastic epoxy over bitumen a try for my boat this time round: https://www.smlmarinepaints.co.uk/primers/two-pack/Ballastic_Epoxy I've just booked her in and was chatting about ordering blacking and I mentioned this - they reckoned that they usually used Jotun 87 and did so over bitumen?! Possibly a misunderstanding somewhere, but anyone had experience of using either over (well prepared) bitumen?

Thanks for all the comments, appreciated

Thanks Tracy