Shotblasting and Zingard

[matthewd]

Dear all,

 

I am looking at buying a lined sailaway and wondering about (i) shotblasting and (ii) Zingard.

 

I figured it ought to be worthwhile doing everything possible to protect the hull at the build stage as an investment over the life of the boat, so I asked the two builders I'm considering about shotblasting.

 

Having reviewed a previous post here, it seems it might not be worth it if the steel provenance is known / certifiable. http://www.canalworld.net/forums/index.php?showtopic=1969&hl=shotblasting. So steel from a reputable builder ought to make it unnecessary, right? What is the magic question I should ask of the builder to find out whether the steel is OK?

 

I was also quoted rather different prices: small builder quoted about 7-800 quid for 40ft hull shotblasting only below the waterline; larger well known builder quoted much more (several hundred pounds per foot!).

 

Secondly, as I was asking about hull protection at the build stage, one builder mentioned a kind of zinc coating called Zingard, cost for painting hull (before blacking) £500. Doesn't seem to have been mentioned on the forums before. Having reviewed the marketing material it seems like an excellent product (of course it would), particularly if any chance of boat going on brackish / sea- water.

 

Has anyone heard of this being used on narrowboats? Overkill perhaps? Or, again, since you only get one opportunity to protect the original bare steel, a worthwhile investment over the lifetime of the boat?

 

Best wishes

Matt

[Gary Peacock]

If the steel is descaled you do not need to shot blast it and most of the hull blackings available are intended to go straight onto steel.

 

I would save your money if I were you.

[DHutch]

However, if its not descaled, then its upto you.

- We did it on emilyanne, shotblasted the whole lot all over, red shotblast primer on within half an hour.

- Followed by twopart zinc epoxy primer, the blacking on the underside, and twopack undercoat/topcoat on the topside.

 

We also did the same on the inside, which in manyways is almost more important at the build stage, because you can never do it as easly ever again. Ask moley about rusty insides...

 

 

 

Daniel

[Callunna]

Ha! Must be going deaf in my old age.

 

We've recently looked at a boat and I thought the owner said he'd applied Zinger. I've even asked about this on another post - shown myself up ... again!

 

So it's Zingard is it?

 

Claims are that it will last 10 years and therefore a widebeam wouldn't need craning out of the water every 3 years to get its bottom blacked (I'm new to this boating lark and I must confess I still have a schoolgirl snigger at that phrase).

 

As there are no facilities near us for lifting a widebeam out of the cut, it would work out pretty expensive to transport the boat to a suitable boatyard (our local places can only deal with narrowbeams).

 

From the posts in this topic, I glean that unless a certain blacking has been used, then it might start coming off as it isn't adhering to the bare steel. Or am I talking through my bottom (not blacked, I might add).

[DHutch]

We do 100+ miles every year, and rairly reblack more then every 4 years, and when we do go into dock the paint is always better than that the boat next door by miles.

- Any visable rusting at all is rair, and what there is no more than a few tiny areas on the most vunerable areas.

 

We could almost certainly leave the boat in the water far longer, 6 or so years, say. And still experience no more rust than many boats that dock every three years. However we continue to dock as frequently as we do because we feel that no visable rusting is a good thing...

- It also makes the preperation and reblacking process a far easyer job. Stick in time and all that.

 

This is the boat in dock this year after four years fequent use.

 

Side veiw before paintin

 

Side close up, painting.

 

The baseplate

 

 

It obvously doesnt look like it was painted a week before, but considering all its had is a good presure washing, looks all right to me. Certianly you can clearly see there is no visable rust anywhere to be seen.

 

 

 

Daniel

[RichardN]

I think it is always worth shot blasting steel and then painting it. You must paint it within 4 hours of shot blasting. Lots of guidance on the web about corrosion eg try http://www.corusconstruction.com/en/refere...work/corrosion/

 

We used to have a share in a boat where rust started coming through within 2 years of first being painted so thought we would try to do better. I found a profesisonal painting outfit halfway between the shell builder and our boat builder and that initially looked very attractive. They would shot blast inside and out and paint using epoxy MIO paint and they suggested taking it right up to the top coat. I did not go for it mainly because the timing did not work but also could not sort logistics of batten fixing.

 

What we could get done in the time was having the outside shot blasted and then painted with zinga (not zinger) http://www.zinga.co.uk/zinga_main.html Our boat builder was busy having nervous breakdowns and going bust as he almost finished our boat so some of my following comments need to be read in that light. Zinga is amazingly expensive. You buy it by the kilogram and as at it is near enough pure zinc you don't get a lot of volume per kilogram. Metaflux, zingard all look similar but we used zinga as Colarado Corrosion Control use zinga and were round the corner from our builder. For some strange reason they applied it by brush, did not spray it. That meant that the base became uneven and needed a lot of filler to get smooth-ish. My top coat seems to be microns thin - circumstances at the time caused that.

 

We have been very lax with repairing gunwale damage and odd funny scrapes - we only run the engine to move the boat and did 400 engine hours last year so say 1000 lock miles? I am impressed as to how little rust we have - the sacrificial action of the zinga is working really well - http://www.hdg.org.uk/221_How_Galvanizing_...l_Explained.php I will wash the boat on Saturday and see what is under the dirt.

 

*I think that shot blasting is excellent, but only if you can get the surface painted within 4 hours

 

The zinga is excellent, I am sure that zingard or any of the other similar products will do equally well. If you can find someone how can shot blast and spray something like a 2 pack epoxy MIO paint on then I think you will get as good a performance but it will be cheaper and the finsih will be better. I can't remember if what was here or on urw that I read of someone using Leigh's resistex paints on their boat. That is a serious paint - see http://www.wjleigh.co.uk/ but they need to be applied by some one with knowledge and also you need to make the decision do you really want a two pack top coat.

[Callunna]

Thanks for the info about Zinga, Richard. I'm quite pleased that the boat we're considering has this applied to it.

 

There were questions raised about the make of this particular boat, but I've had an experienced boatbuilder check it out and the report is very favourable.

 

I'm coming to the conclusion that if you ask 100 boating people their opinion, you'll get 101 different answers. This makes it very confusing for us newbies

[blackrose]

Thanks for the info about Zinga, Richard. I'm quite pleased that the boat we're considering has this applied to it.

 

There were questions raised about the make of this particular boat, but I've had an experienced boatbuilder check it out and the report is very favourable.

 

I'm coming to the conclusion that if you ask 100 boating people their opinion, you'll get 101 different answers. This makes it very confusing for us newbies

 

I'm also confused about this zinga/zincguard stuff. Someone has mentioned sacrificial action (from a paint product?) If this is the case (which I very much doubt) steel craft on inland waterways are supposed to use magnesium, not zinc anodes.

 

Anyway, yes you will get 101 different answers but that's the beauty of the forum. Then you have to make your own mind up.

Edited July 15, 2007 by blackrose

[DHutch]

... I can't remember if what was here or on urw that I read of someone using Leigh's resistex paints on their boat. That is a serious paint - see http://www.wjleigh.co.uk/ but they need to be applied by some one with knowledge and also you need to make the decision do you really want a two pack top coat.

Might well have been here, we have used Leighs paints thought the boat.

- No personal connection as such, other than our family have been using there products for 40years and never been other than very happy. There customer service and technical support is excellent as well.

 

 

The paints we use are.

Resistex C137V2 Special Finish - Topcoat (acrylic urethane gloss )

Resistex C237 Undercoat/Sheen Finish - Undercoat (polyurethane undercoat)

Resistex M535 Pitch Free Underwater Primer - Blacking (vinal primer)

Metagard L574 Blast Primer - Shotblast Primers (twopart primer)

Epigrip M902 Winterfast Hi-Build Brushing Aluminium - Primer (epoxy aluminum)

Epigrip J984 Zinc Rich Primer Zinc Epoxy Primer

- And then some one pot sign writing paint for the coach-lines after the latex gloves come off.

 

The 'luxary narrowboat' Phoenix 58 also uses leighs paints. Although they sprayed it rather than rollering in on and havnt managed to get as good a finish.

 

 

 

 

 

 

Daniel

[RichardN]

Might well have been here, we have used Leighs paints thought the boat.

- No personal connection as such, other than our family have been using there products for 40years and never been other than very happy. There customer service and technical support is excellent as well.

 

Well done!

[Big Steve]

However, if its not descaled, then its upto you.

- We did it on emilyanne, shotblasted the whole lot all over, red shotblast primer on within half an hour.

- Followed by twopart zinc epoxy primer, the blacking on the underside, and twopack undercoat/topcoat on the topside.

 

We also did the same on the inside, which in manyways is almost more important at the build stage, because you can never do it as easly ever again. Ask moley about rusty insides...

 

 

 

Daniel

 

Don't know much about paint, but thought epoxy was best straight onto steel, also thought it would react with a normal paint, eg shotblast primer. As I'm about to do mine any comments would be appreciated.

 

Steve

[DHutch]

Don't know much about paint, but thought epoxy was best straight onto steel, also thought it would react with a normal paint, eg shotblast primer. As I'm about to do mine any comments would be appreciated.

 

Steve

I can only suggest you contact the suppler for exact details on your paint system, as im not a expert myself.

- However we use there blast primer, with the zinc epoxy over that, then either the polyurethene of the vinal blacking over that.

- We have also used the aluminum epoxy stright onto bright steel, which also works well, but the steel does have to be very bright.

 

 

 

Daniel

[matthewd]

Thanks for all these comments - very interesting.

 

The Zinga / Zingard products are apparently a different thing (not a paint at all) from the zinc epoxy primer and the comment about sacrificial action (mentioned by Blackrose) is correct according to the Zingard marketing material: http://www.mgduff.co.uk/zingard-faq.html . But does this mean it's inappropriate for inland waterways?

 

Richard N's experience sounds positive: an important remaining question is what if any blacking / additional hull paint is applied on top of the zinc coating? I guess not all are compatible.

 

Thanks all,

Matt

[blackrose]

Thanks for all these comments - very interesting.

 

The Zinga / Zingard products are apparently a different thing (not a paint at all) from the zinc epoxy primer and the comment about sacrificial action (mentioned by Blackrose) is correct according to the Zingard marketing material: <a href="http://www.mgduff.co.uk/zingard-faq.html" target="_blank">http://www.mgduff.co.uk/zingard-faq.html </a>. But does this mean it's inappropriate for inland waterways?

 

I would think that a zinc based paint offers anti-corrosive properties in any waters including inland, but that doesn't work through galvanic action - after all you wouldn't want your primer to become sacrificial!

[matthewd]

I would think that a zinc based paint offers anti-corrosive properties in any waters including inland, but that doesn't work through galvanic action - after all you wouldn't want your primer to become sacrificial!

 

Does this mean sacrificial?: (from website)..

 

quote:

 

Q. How does Zingard work?

A. It reacts with the parent metal to form an electrolytic bond, which results in a potential of 1040mV between the steel and the zinc. Once the steelwork becomes wet, the zinc ions go into dissolution and the current begins to flow from the zinc to the steel, depleting the zinc layer and protecting the steel beneath.

 

Q. What if Zingard is scratched through to the bare metal?

A. Zingard has a 3 – 5mm ‘throw’, which means that unprotected metal up to 3 – 5 mm away from a Zingarded surface will be protected. It will form a layer of surface rust, but there will be no pitting beneath the rust. On small areas like scratches and chips, the surface will often go a light brown-grey colour.

 

end quote

 

Interesting, no? Anyway, the "brand-name" shell builder I have been speaking to has advised against it (because not sure about paint compatibility, and the boats they build are still going strong after 30 years without it..), even if the smaller builder I spoke to thought it might be a good idea!

 

Regards

Matt

Edited July 20, 2007 by matthewd

[NB Willawaw]

One of the things I have found about using unusual paints or blacking is that its fine when the boat is being built but when you come up to the scheduled drydocking, its a hell of a job to get the boatyard to buy in to what you want. Most yards who do drydocks and blacking just want to slap it on and move on to the next boat. I used Jotun products when the boat was built and I was lucky with the first docking at 2 years (the yard I chose were very helpful), but now I'm approaching the second docking at 4 years, I'm finding it hard to select a dock that will play.

[DHutch]

One of the things I have found about using unusual paints or blacking is that its fine when the boat is being built but when you come up to the scheduled drydocking, its a hell of a job to get the boatyard to buy in to what you want. Most yards who do drydocks and blacking just want to slap it on and move on to the next boat. I used Jotun products when the boat was built and I was lucky with the first docking at 2 years (the yard I chose were very helpful), but now I'm approaching the second docking at 4 years, I'm finding it hard to select a dock that will play.

Which is why we dock at worsley.

- Bring your boat, bring you paint, bring your freinds, and give everyone a paint brush and tea on the hour.