Jump to content

Vactanning the hull


XLD
 Share

Featured Posts

I haven't, but the chap with a widebeam next to my barge did and he had to re-black after two seasons. 

 

I used glass flake epoxy and 10 years on it looks just as it did the year I applied it, apart from being less shiny. It does sparkle a tiny bit now where the glass flakes catch the light.

Link to comment
Share on other sites

1 hour ago, Bargebuilder said:

I haven't, but the chap with a widebeam next to my barge did and he had to re-black after two seasons. 

 

I used glass flake epoxy and 10 years on it looks just as it did the year I applied it, apart from being less shiny. It does sparkle a tiny bit now where the glass flakes catch the light.

They used that on the Iron Bridge 20 years ago or so, it was still in good nick apart from mechanical damage when they repainted it again about 3 years ago..  Excellent stuff.

Link to comment
Share on other sites

1 minute ago, Bee said:

They used that on the Iron Bridge 20 years ago or so, it was still in good nick apart from mechanical damage when they repainted it again about 3 years ago..  Excellent stuff.

I understand too that it has been used on the Forth Bridge, so the old saying about painting the said bridge no longer applies!

Link to comment
Share on other sites

I have often wondered why steel boats are "blacked" with bitumen based coatings.

I always thought (wrongly?) that this stuff was for wooden hulls.

Surely a modern outdoor paint would be more durable.

Link to comment
Share on other sites

3 hours ago, Mad Harold said:

I have often wondered why steel boats are "blacked" with bitumen based coatings.

I always thought (wrongly?) that this stuff was for wooden hulls.

Surely a modern outdoor paint would be more durable.

I should think that you're right.

 

There are epoxy tars which are much more durable than traditional blacking, but there is nothing I know that out-performs glass flake epoxy.

 

The principle is that the microscopic platelets of glass in the coating align themselves parallel with the surface of the steel, overlapping to make the surface extremely resistant to abrasion; as hard as glass (well much harder than other coatings anyway).

The stuff is used to protect the cooling water intakes of power stations, so it is highly trusted by industry.

 

It is a bit more expensive than blacking (but not that much) and the preparation needed is higher, but the long term cost savings of not needing to haul out or dry dock and re-black every three years could be considerable. 

 

My boat was coastal so in salt water and as I mentioned showed no sign of degradation in many years, so in fresh water, a much less aggressive environment, it should perform even better.

 

I used 'Chemco International' if anyone wants to research the product further.

Link to comment
Share on other sites

7 hours ago, XLD said:

Has anyone used Vactan on the hull before blacking?

Yes. I used it under Rylards bitumen based blacking which, due to Covid restrictions, was left on a  year longer than planned until the boat finally came out this May - I was very relieved to see how well it had  performed. So much so that I've now used it under 2 coats of SML's 2 pack epoxy primer followed by 2 coats of Jotun 90. Time will tell I suppose.

Link to comment
Share on other sites

19 minutes ago, Sea Dog said:

So much so that I've now used it under 2 coats of SML's 2 pack epoxy primer followed by 2 coats of Jotun 90. Time will tell I suppose.

 

Sounds odd to put a water based rust converter under epoxy. If you are going to get the best out of epoxy you should gritblast back to bare metal, in which case there would be no rust to convert.

Link to comment
Share on other sites

5 minutes ago, David Mack said:

 

Sounds odd to put a water based rust converter under epoxy. If you are going to get the best out of epoxy you should gritblast back to bare metal, in which case there would be no rust to convert.

Going back to bare metal is always best if one can. Grit blasting will certainly do it, but pure water blasting will do it to, with very little mess to clear up afterwards, apart from the rubbish that's been stripped off. I watched a water blasting operative demonstrate the equipment by putting a house brick on the ground and cutting it in half; easily!

 

There is also a hybrid between the two that I've used and works very well. It is wet media blasting, at a much lower pressure than pure water blasting, but has an abrasive grit in small quantities that is introduced into the water and does most of the work.

 

Wet blasted steel gingers (rusts) very quickly, so a surface tolerant epoxy primer should be used that will stick to wet, 'gingered' steel.

 

I used one recommended by Chemco as did the chap working on the boat next to mine. He was applying it by roller but half way through the job it started to rain, heavily. His roller tray part filled with rain water so he pushed the roller through this water and carried on until he had finished his hull. Three years later, he still hadn't added a top coat, but the primer showed no signs of failing and there was no rust showing where he had applied it.

 

These modern coatings are good, very good!

 

Link to comment
Share on other sites

What you have to bear in mind about Vactan is that it's a rust converter. It converts the rust into a surface suitable for painting over. If you paint it over bare shiny metal it has no grip and will just form a skin which will flake off.

 

I've used it really successfully in the past by applying over rust...then lightly wire brushing the treated area before painting. I don't use it on non-rusty bare metal. That needs an acid primer.

 

Bob

 

Link to comment
Share on other sites

3 hours ago, David Mack said:

 

Sounds odd to put a water based rust converter under epoxy. If you are going to get the best out of epoxy you should gritblast back to bare metal, in which case there would be no rust to convert.

 

Yes I completely agree with all of that. Can't understand why anyone would use vactan under epoxy.

Link to comment
Share on other sites

9 hours ago, Bargebuilder said:

Blacking is traditional, but it doesn't always last, as very well illustrated in this YouTube offering where the blacking, although professionally applied, lasted for less than a year.

 

https://youtu.be/PwnHVzmdn40

 

 

Not sure which one you used but Jotun also do a glass flake epoxy.

 

I used 2 coats of Jotun aluminum flake epoxy which is also very abrasion resistant (but perhaps not as much as the glass flake) followed by 2 coats of the same epoxy without the aluminum in black. I only chose that system as I'd used it at work so I knew what I was doing.

 

6 years on and it's still looking perfect.

Link to comment
Share on other sites

16 minutes ago, blackrose said:

 

Not sure which one you used but Jotun also do a glass flake epoxy.

 

I used 2 coats of Jotun aluminum flake epoxy which is also very abrasion resistant (but perhaps not as much as the glass flake) followed by 2 coats of the same epoxy without the aluminum in black. I only chose that system as I'd used it at work so I knew what I was doing.

 

6 years on and it's still looking perfect.

I'm sure that Jotun is very good, the company certainly has an excellent reputation. I expect that International do one as well, but what attracted Chemco International to me was the price of its products and who it's customers are. It was a case of, if it's good enough for them, then it will do the job for me.

 

They formulate and manufacture their own coatings and sell them for use on oil rigs and power stations etc. 

 

When I dealt with them they were about half the price of glass flake products retailed by 'hobby' marine paint  suppliers.

 

One spin off from using this coating has been that zero steel has ever been in contact with the water, so zero corrosion has occurred and apart from the stern gear, the plentiful anodes have had nothing to protect, so after 9 years there is very little wasting of the, in my case, zinc anodes.

 

Another huge advantage of the glass flake epoxy I used is that it doesn't have to be removed or abraded, simply pressure washed clean before it can be over-coated; if that is, it ever needs doing🤞😁.

Link to comment
Share on other sites

7 hours ago, blackrose said:

That's interesting, I didn't know that. Seems counter-intuitive not to give an old coating a key before recoating.

It does need to be clean of course, hence the need to pressure wash, but not abraded.

 

When first applied, the surface is very glossy as there is a film of epoxy covering the flakes of glass, much like the pebbles in concrete being barely visible after its surface has been 'floated'. Over the years, as the surface of the epoxy is weathered, a thin layer of surface epoxy disappears and along with it the gloss, leaving the twinkling flakes of glass slightly exposed. The surface texture is a bit like very fine abrasive paper and perfect for receiving further coatings. 

 

Given correct preparation of the steel before the original primer was applied, there will be no detachment of the original paint, so overcoating can be done with complete confidence.

 

If desired, the glass flake epoxy can do its job of protecting the steel, whilst another paint in the colour of your choice can be applied over it as a cosmetic finish. 

 

Unwisely, on my barge, not knowing how brilliant the stuff was going to be, I only painted the hull and topsides, relying on more traditional paint systems for the deck and cabin roof. After 9 years, there was no sign of rust below the (salt) water line, but patches of rust in a number of places where I hadn't epoxied.

Link to comment
Share on other sites

15 hours ago, Bargebuilder said:

I should think that you're right.

 

There are epoxy tars which are much more durable than traditional blacking, but there is nothing I know that out-performs glass flake epoxy.

 

The principle is that the microscopic platelets of glass in the coating align themselves parallel with the surface of the steel, overlapping to make the surface extremely resistant to abrasion; as hard as glass (well much harder than other coatings anyway).

The stuff is used to protect the cooling water intakes of power stations, so it is highly trusted by industry.

 

It is a bit more expensive than blacking (but not that much) and the preparation needed is higher, but the long term cost savings of not needing to haul out or dry dock and re-black every three years could be considerable. 

 

My boat was coastal so in salt water and as I mentioned showed no sign of degradation in many years, so in fresh water, a much less aggressive environment, it should perform even better.

 

I used 'Chemco International' if anyone wants to research the product further.

I looked at Chemco's site and it certainly is impressive. It would seem to be the obvious choice these days. I'm surprised I've not heard about it before.

Link to comment
Share on other sites

1 minute ago, XLD said:

I looked at Chemco's site and it certainly is impressive. It would seem to be the obvious choice these days. I'm surprised I've not heard about it before.

Impressive is the word.

 

The narrowboating world is, on the whole, quite a traditional one. Boatyards like to apply what they know, and narrowboaters are largely guided by what the boatyard offers. 

 

Also, Chemco is a commercial company, mainly selling its product by the lorry load to water companies and other huge organisations, so it's web site reflects that. However, the sales team and technical advisor are great and very happy to sell in small quantities when asked.

 

It's the fact that they are not 'yachty' paint suppliers that keeps their prices so reasonable.

It wouldn't be a good business model to paint boats in a finish that could last for 20 to 30 years, so boatyards are going to be unwilling to use glass flake.

Link to comment
Share on other sites

14 hours ago, David Mack said:

 

Sounds odd to put a water based rust converter under epoxy. If you are going to get the best out of epoxy you should gritblast back to bare metal, in which case there would be no rust to convert.

Yup, that's certainly the conventional wisdom. This year, however, I've hand tooled back to the metal and used SML's Ballastic Black 2 pack Epoxy Primer (not to be confused with their Ballastic Black bitumen based blacking). Their claim is that it is surface tolerant and specifically bitumen tolerant. This is supposed to give a sound base for the Jotun 99 applied as topcoat. The Vactan therefore is to address any rust left from the hand prep, which is clearly not going to be as thorough as grit blast. Time will tell, but it's hardly any dearer than decent blacking and, judging by how it's faired so far, is more abrasion resistant than bitumen. If it lasts no longer than bitumen so be it, but it's hard to think it'll be worse, especially given the increasingly common diesel slicks I've been through on the Grand Union already.

Link to comment
Share on other sites

5 hours ago, Sea Dog said:

The Vactan therefore is to address any rust left from the hand prep, which is clearly not going to be as thorough as grit blast.

 

I'd be more inclined to use Fertan for that application, and obviously washing off the residue isn't a major problem on the hull.

Link to comment
Share on other sites

5 hours ago, TheBiscuits said:

 

I'd be more inclined to use Fertan for that application, and obviously washing off the residue isn't a major problem on the hull.

That's also the combo Keelblack specify I believe. I had a chat with Mr Fertan when he was looking at a boat who's Keelblack had failed rather dramatically and he kindly gave me some.

 

I'm a bit reticent to get the hull prepped and then apply water to wash the fertan off but, hey, were in Britain - it'll rain for a month solid anyway!

 

So far I've never been anything but entirely happy with Vactan. That might change if my new blacking falls off(!), but it didn't last time and I've paid my money and taken my choice now.

Link to comment
Share on other sites

1 minute ago, Sea Dog said:

So far I've never been anything but entirely happy with Vactan. That might change if my new blacking falls off(!), but it didn't last time and I've paid my money and taken my choice now.

 

Fair enough.  I'm a Vactan fan too, in fact I have been using it this afternoon.  I will be using Fertan for the same job you are doing in a fortnight though because I think it's the better product for that particular application.

 

 

Link to comment
Share on other sites

3 minutes ago, TheBiscuits said:

 

Fair enough.  I'm a Vactan fan too, in fact I have been using it this afternoon.  I will be using Fertan for the same job you are doing in a fortnight though because I think it's the better product for that particular application.

 

 

Now you tell me! ;)

 

Link to comment
Share on other sites

12 hours ago, Bargebuilder said:

Impressive is the word.

 

The narrowboating world is, on the whole, quite a traditional one. Boatyards like to apply what they know, and narrowboaters are largely guided by what the boatyard offers. 

 

 

The other reason of course it's that epoxies are more technical paint systems. As well as good steel preparation (from new or if changing from bitumen) one needs to take care to mix epoxies properly according to weight or volume as well as pay attention to minimum and maximum overcoating times according to ambient temperature. 

 

Most boat yards can't be bothered with all that and would simply rather just slap on a couple of coats of bitumen. It keeps their expensive dry docks, slipways and cranes busier too!

Edited by blackrose
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
 Share

  • 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.