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Epoxying the baseplate


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After grit blasting my plan was to stipple the first coat on with a wallpaper brush to get it into any pits, welds or uneven areas, and then roller on subsequent coats. That's how I painted the sides. 

 

I normally thin the first coat of jotamastic with 10% thinners to get it to flow into the recesses, but I think I'll avoid doing that as it will just drip onto me. For those who've actually painted their baseplates, even if it's just with bitumen, is there any technique to keeping it on the steel and not dripping all over you, or is it just a case of not overloading the brush or roller?

 

I'm not interested in comments or discussions about whether it's worth painting the baseplate as it's been done to death. 

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I brushed on first coat and rollered on the second.

Just don’t overload the brush,

I think I used a 4” brush, but I have a much smaller area to cover than yourself. 
It may also be stating the obvious but wear goggles and gloves.

 

And, presuming you’re lying on your back, lay to the side of where you’re painting above, so don’t paint above yourself.

If that makes sense. 

The fumes off my paint were horrible, so paint up wind if possible and reposition yourself under the unpainted section.

 

I don’t think a wallpaper brush would be ideal, the proportion wouldn’t be right.

Wouldn’t hold enough paint properly. 

But 🤷‍♀️try it and see.

 

Or perhaps do as Mike above suggests.

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17 minutes ago, Goliath said:

I brushed on first coat and rollered on the second.

Just don’t overload the brush,

I think I used a 4” brush, but I have a much smaller area to cover than yourself. 
It may also be stating the obvious but wear goggles and gloves.

 

And, presuming you’re lying on your back, lay to the side of where you’re painting above, so don’t paint above yourself.

If that makes sense. 

The fumes off my paint were horrible, so paint up wind if possible and reposition yourself under the unpainted section.

 

I don’t think a wallpaper brush would be ideal, the proportion wouldn’t be right.

Wouldn’t hold enough paint properly. 

But 🤷‍♀️try it and see.

 

Or perhaps do as Mike above suggests.

 

Thanks. Actually wearing goggles wasn't obvious but now you mention it, it is!

 

I used a wallpaper brush for the sides and it worked pretty well. Where I'm going I can actually stand up although I might be crouching. Probably terrible for one's back. 

29 minutes ago, Mike Adams said:

Hire an airless spraygun - you will get even coverage and it will go into the pits. I believe it costs about £100 a day. Not much compared to the shotblasting and paint.

 

Thanks, I'll look into it. 

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12 hours ago, blackrose said:

For those who've actually painted their baseplates, even if it's just with bitumen, is there any technique to keeping it on the steel and not dripping all over you, or is it just a case of not overloading the brush or roller?

I suppose it depends on the coating: I used a two pack glass flake epoxy and applied it with a 9" roller. I only had less than 2 feet of clearance so I was laying on my back but the stuff didn't drip, hardly at all and went on very nicely. The product is incredibly hard because of the included glass flakes and it's suggested that it should last for 25 years; only time will tell but that was 11 years ago and it is showing no signs of coming off yet.

 

Have fun!

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12 hours ago, Bargebuilder said:

I suppose it depends on the coating: I used a two pack glass flake epoxy and applied it with a 9" roller. I only had less than 2 feet of clearance so I was laying on my back but the stuff didn't drip, hardly at all and went on very nicely. The product is incredibly hard because of the included glass flakes and it's suggested that it should last for 25 years; only time will tell but that was 11 years ago and it is showing no signs of coming off yet.

 

Have fun!

 

Arguably the glass flake stuff is the ultimate in underwater protection but it's meant for abrasion resistance. Was your glass flake epoxy Jotamastic? I'm using the Jotamastic 90 aluminum flake epoxy. It's also pretty good stuff. I put 2 coats on the sides, followed by 2 coats of Jotamastic black epoxy 7 years ago and it's still looking perfect. 

Edited by blackrose
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14 hours ago, blackrose said:

 

Arguably the glass flake stuff is the ultimate in underwater protection but it's meant for abrasion resistance. Was your glass flake epoxy Jotamastic? I'm using the Jotamastic 90 aluminum flake epoxy. It's also pretty good stuff. I put 2 coats on the sides, followed by 2 coats of Jotamastic black epoxy 7 years ago and it's still looking perfect. 

That was my conclusion after much research. It is used commercially on oil rigs, ships ballast water tanks, power station cooling water intakes and the Fourth bridge, because they got fed up with painting it: they expect it to last for 25 years.

 

My barge has spent its life in sea water, arguably a more aggressive environment than fresh water and it's doing very well after 11 years. 

 

Surely resistance to abrasion is exactly what one needs and having tried to get it off with an abrasive wheel I can vouch for that.

 

Mine came from Chemco International in Scotland as it was much cheaper than products from 'yachtie' suppliers.

 

They also do a surface tolerant primer that can be applied to poorly prepared surfaces and even to damp surfaces for example immediately after wet blasting, even if the steel has 'gingered'. 

 

It is a superb product, easy to apply and very little smell unlike some other coatings.

 

A little more expensive perhaps, but only in the short term. 

 

Another spin off is a saving in anodes, as there is no exposed steel to protect. Apart from the stern gear, the hull anodes are only protecting the steel studs with which they are attached.

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16 minutes ago, Bargebuilder said:

Surely resistance to abrasion is exactly what one needs and having tried to get it off with an abrasive wheel I can vouch for that.

 

Mine came from Chemco International in Scotland as it was much cheaper than products from 'yachtie' suppliers.

 

They also do a surface tolerant primer that can be applied to poorly prepared surfaces and even to damp surfaces for example immediately after wet blasting, even if the steel has 'gingered'. 

 

It is a superb product, easy to apply and very little smell unlike some other coatings.

 

A little more expensive perhaps, but only in the short term. 

 

Another spin off is a saving in anodes, as there is no exposed steel to protect. Apart from the stern gear, the hull anodes are only protecting the steel studs with which they are attached.

We have recently applied the Chemco surface tolerant primer as a touch-up to the abraded areas of ours. Not sure what the original epoxy was but it didn't hold up well. Early days, but I can say it went on well and, despite only being primer at the time, it held up very well to the bumps and scrapes of the BCN Challenge. My wife went back the week after to touch in any damage and start topcoating - there were virtually no areas where we had damaged it at all.

 

Helpful people to deal with directly too.

 

Alec

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22 minutes ago, Bargebuilder said:

 

Surely resistance to abrasion is exactly what one needs and having tried to get it off with an abrasive wheel I can vouch for that.

 

Yes, that's certainly part of what you need. I've found that the Jotamastic aluminum flake epoxy has good abrasion resistance and the only reason I didn't use the glass flake version was because I heard it was more difficult to apply properly (diy).

 

Personally I'd always go for Jotamastic as I used it for a couple of years when I worked in a boatyard and I understand the product. 

 

What's the actual paint you used? Is it made by Chemco International or are they just the supplier?

11 minutes ago, agg221 said:

We have recently applied the Chemco surface tolerant primer as a touch-up to the abraded areas of ours. 

 

Is that two-part epoxy primer? Many epoxies are designed to be applied direct to steel without any primer. The epoxy is the primer. So when I hear about people using primer in conjunction with epoxy it raises some questions for me. 

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4 minutes ago, blackrose said:

What's the actual paint you used? Is it made by Chemco International or are they just the supplier?

Chemco International is the manufacturer. They are a fairly small company, mostly supplying directly to the offshore Oil & Gas market but they do know their products are being sold into the inland waterways as they have some chandlers which stock them (this came from a conversation with them). Because they are not specifically targeting growing that market they have one price per kg, so you pay the same as the chandler rather than a deliberate mark-up. I found they offered good technical support, which is needed in their primary market.

 

Yes - it's a two part epoxy primer. Primers are usually of slightly different formulation to topcoats as they include components designed to react with/bond to the surface. These components can be varied depending on the intended surface, so the bonding agents to react with/bond to iron oxide would be slightly different from those designed for a clean steel surface and some will work on a water wet surface whereas others will not. Adding these is unnecessary in a topcoat which gives a slightly stronger final bonded lattice as more of the volume can cross-link, resulting in a slightly tougher coating. Because the effect is fairly minor, a self-priming epoxy will not be significantly worse than a dedicated topcoat. I wouldn't use a dedicated topcoat as a primer though. Personally, on bare steel I would use a standard self-priming epoxy but on pitted steel I would never be confident of having got it properly clean in a cost-effective way, even by blasting, as the size of the blast media limits which pits are fully cleaned out and experience of repeated cycles of blasting/phosphating has shown that rust will blow through for several cycles (on really badly pitted steel that can take up to 4 cycles) which is obviously not practical when blacking a boat. I would therefore go for the surface tolerant primer and then a topcoat. In our case it made sense as we are doing in-water touch-up of abraded areas so the preparation is minimal, being nothing more than a hand wire brushing, and the formulation is designed to cope with that.

 

FWIW some of my background is in industrial painting processes, mainly surface preparation but it has brought me in contact with a need to understand the formulation approach (and once upon a time I was a chemist so I do have something to draw on, although I was generally inorganic).

 

Alec

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13 minutes ago, blackrose said:

Is that two-part epoxy primer? Many epoxies are designed to be applied direct to steel without any primer. The epoxy is the primer. So when I hear about people using primer in conjunction with epoxy it raises some questions for me. 

Chemco RA500M is in fact a two pack  epoxy and it is a moisture tolerant, surface tolerant primer.

 

The chap in the yard next to my barge was applying it to his boat when half way through the job it started to rain. He continued to roller it onto wet steel and in the end, the 'paint' in the tray had several mm of rain water on top of it through which he pushed the roller to charge it. That boat sat there for the next 4 years with nothing but that original coating of RA500M and it held up brilliantly.

 

I wouldn't use a non-epoxy primer before an epoxy top coat either.

 

The glass flakes align to the steel surface forming a glass hard barrier which logic suggests is a lot harder than aluminium, plus, glass is inert which aluminium certainly is not.

 

I applied 2 coats of 2 pack epoxy primer followed by 5 coats of glass flake epoxy top coat, all with a 9" roller, and it went on very nicely indeed, one coat each day for a week.

 

An airless spray is the alternative if you have one.

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Yes glass is inert but it does not have the same anticorrosive barrier properties of the aluminum flake epoxy. They both have their benefits, you takes your pick... As I said, I used the aluminum flake as I have experience of using it and I heard the glass flake epoxy was more difficult to apply as a DIYer. Whether that's true in practice I have no idea. 

 

I obviously haven't read the TDS for your glass flake paint, but if I was using the Jotamastic equivalent I'd have applied a couple of coats direct to the steel followed by 2 coats of Jotamastic black. No primer required. 

 

This is the aluminum flake version. 

 

https://www.rawlinspaints.com/home/metal-paints/direct-to-metal-paints/5032-jotun-jotamastic-90-aluminium-wg.html

 

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2 hours ago, blackrose said:

Yes glass is inert but it does not have the same anticorrosive barrier properties of the aluminum flake epoxy.

The best anti-corrosive property of a coating is the ability to exclude water and oxygen from the steel. Glass flake is much harder than aluminium flake, so perhaps it would be less likely to erode or be scratched.

 

Presumably the people who chose glass flake over aluminium flake for the Fourth Bridge evaluated both coatings.

 

Chemco will despatch sample 1l tins of their products if you need confirmation that they are easy to apply, adhere brilliantly and give an excellent finish.

 

If you buy enough, Chemco will even mix it to any RAL colour.

 

Give it a try, you might just be converted, especially if it is cheaper.

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On 30/06/2022 at 20:27, blackrose said:

 

Thanks. Actually wearing goggles wasn't obvious but now you mention it, it is!

......

I'd wear a mask to cover your mouth and nose as well.

A lot of the fumes from paint are heavier than air so you are much more exposed to them if you're underneath the thing your painting. Also handy for stopping random drips ending up in your mouth.

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3 hours ago, Barneyp said:

I'd wear a mask to cover your mouth and nose as well.

A lot of the fumes from paint are heavier than air so you are much more exposed to them if you're underneath the thing your painting. Also handy for stopping random drips ending up in your mouth.

Another advantage of Chemco's product is that it has zero solvent and VOCs and is 100% solids so no fumes.

 

Not a real issue when outside in the open, but they do equally excellent coatings for the inside of steel water tanks that are drinking water safe and working in confined spaces this feature is much more important.

 

This is lifted from their website for anyone interested. 

  • Solvent-free
  • Wet tolerant – Can be applied on soaking wet surfaces
  • Excellent chemical resistance and abrasion properties
  • Glassflake-reinforced for added protection
  • Can be applied in any environmental condition
  • No operational shutdown; nearby work can continue without disruption
  • 100% solid / Zero VOC
  • NSF certified for potable water applications
  • User-friendly with high flexibility and ease of application
  • No recoating limitations
  • No humidity or dew point restrictions
  • Health & Safety risk and Fire Hazard significantly reduced
  • Quick back-in-service times

 

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8 hours ago, Bargebuilder said:

Chemco RA500M is in fact a two pack  epoxy and it is a moisture tolerant, surface tolerant primer.

 

The chap in the yard next to my barge was applying it to his boat when half way through the job it started to rain. He continued to roller it onto wet steel and in the end, the 'paint' in the tray had several mm of rain water on top of it through which he pushed the roller to charge it. That boat sat there for the next 4 years with nothing but that original coating of RA500M and it held up brilliantly.

 

I wouldn't use a non-epoxy primer before an epoxy top coat either.

 

The glass flakes align to the steel surface forming a glass hard barrier which logic suggests is a lot harder than aluminium, plus, glass is inert which aluminium certainly is not.

 

I applied 2 coats of 2 pack epoxy primer followed by 5 coats of glass flake epoxy top coat, all with a 9" roller, and it went on very nicely indeed, one coat each day for a week.

 

An airless spray is the alternative if you have one.

 

 

Thinking of doing our narrow boat next year. Probably sides only, not base plate, though we will see how it goes.

 

I was looking primarily at the Jotmastic 90, but this Chemco product looks interesting. Could you confirm if you used  2 coats of their RS500P (epoxy primer), followed 5 coats of RA500m (glass flake single coat/topcoat) please?

 

I also read a company called Sherwin Williams are a good company to approach regarding epoxy coatings, so might investigate them further.

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4 minutes ago, rusty69 said:

 

 

Thinking of doing our narrow boat next year. Probably sides only, not base plate, though we will see how it goes.

 

I was looking primarily at the Jotmastic 90, but this Chemco product looks interesting. Could you confirm if you used  2 coats of their RS500P (epoxy primer), followed 5 coats of RA500m (glass flake single coat/topcoat) please?

 

I also read a company called Sherwin Williams are a good company to approach regarding epoxy coatings, so might investigate them further.

It was eleven years ago, but I'm pretty sure, now you mention the product codes, that that is exactly the system and number of coats I used. I followed the advice of their technical team which proved to be excellent; give them a call.

 

A friend of mine used a competitors glass flake product to which he had to add solvent to make it workable and it was more difficult to apply and it didn't perform as well either. It tore apart any rollers he used and he eventually used an airless spray at considerable expense and faff with cleaning between uses, whereas the Chemco products for me went on easily with a short to medium pile quality roller and of course no solvents at all.

 

I was aiming for a 500 micron depth and achieved that with 7 coats. I purchased if I remember correctly 80kg between the two products, plus a different coating for the inside of my built-in steel tanks.

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3 minutes ago, Bargebuilder said:

It was eleven years ago, but I'm pretty sure, now you mention the product codes, that that is exactly the system and number of coats I used. I followed the advice of their technical team which proved to be excellent; give them a call.

 

A friend of mine used a competitors glass flake product to which he had to add solvent to make it workable and it was more difficult to apply and it didn't perform as well either. It tore apart any rollers he used and he eventually used an airless spray at considerable expense and faff with cleaning between uses, whereas the Chemco products for me went on easily with a short to medium pile quality roller and of course no solvents at all.

 

I was aiming for a 500 micron depth and achieved that with 7 coats. I purchased if I remember correctly 80kg between the two products, plus a different coating for the inside of my built-in steel tanks.

Many thanks. I will give them a call.

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Another huge advantage of using a glass flake coating on one's hull, is that when the time comes to advertise your boat for sale, it stands out from almost every other vessel, is more desirable and commands a higher price; well it did with my barge.

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