Chemco Protective Coatings - Roof Treatment

[Alex Cat]

Hi.

 

I need my roof treating. It has some rust areas - not too much but I'm about to place some semi-flexible solars and so need the roof A1 before fixing.

 

I've been offered a quote using paints supplied by Chemco International.

In particular, these:
http://marine.chemcoint.com/products/applications/topsides-and-boottop.html

 

I'm wondering if folks here have any thoughts on these paints.

Many thanks.

[WotEver]

Looks great on their website 

Never used it though so can't comment on longevity or reliability. 

[Alex Cat]

I am very interested and I think I'm going to go for it.

Will report back!

[WotEver]

8 hours ago, Alex Cat said:

I am very interested and I think I'm going to go for it.

Will report back!

Please do

[Alex Cat]

Surprised no-one else is interested in the thread.

i always thought primers and paint were the makings of good boat chitchat ☹️

[Phil Ambrose]

Perhaps many others have been like me and have just just been reading and not felt the need to comment.

Phil

[Alex Cat]

And there's me thinking my topic was boring.

Love to hear people's experience, thoughts, insights on using a commercial sector marine treatment on a 'non-commercial' vessel.

[Sea Dog]

8 hours ago, Alex Cat said:

 

Love to hear people's experience, thoughts, insights on using a commercial sector marine treatment on a 'non-commercial' vessel.

During my time with the Royal Navy, we moved from fairly frequent painting by ship's staff with support from dockyard painters at longer intervals to commercial sector companies doing the work with more technical coatings and specialist techniques at long intervals with the crew not being allowed to interfere in the interim. This was necessitated not just because of advances in paint technology and techniques, but also because ship's crews got smaller whilst the ships got bigger. There were other operationally based reasons too, but the result was the same.  However, also during that time, warships went from being habitually shiny and smart (albeit with rather thick coatings in some areas!) to looking like Russian trawlers.

I think, therefore, that high tech coatings have their place, particularly in areas where they cannot be easily maintained between dockings and an epoxied hull might be a good example of this. Where self-help maintenance is possible, however, perhaps simpler, more traditional coating systems still offer a viable, perhaps even more desirable, alternative. 

How's that as a starter, Alex Cat?

[Alex Cat]

HAH - that'll do!

[Tony Brooks]

As conventional paint systems have been shown to be porous, especially when something traps damp against the paint film, I would want to get some idea about how the porosity compares. I would also want to know  about the shelf life of the product that is "left over". If its only available in 5 litre cans or larger and its like ordinary paint I suspect it might involve a lot of waste.

[Dr Bob]

Answering the OP's first post, this looks to be a good product backed by a good number of case histories. I took a look at the product data sheets and it certainly looks good. The ''primer" is claimed to work well on a well cleaned rusted surface so it should work reasonably well on your roof.

I do have some concerns though. This looks to be targetted at large industrial applications and will therefore have been optimised for airless spray application (at least for the top coat). It may well be 'brushable' but there are trade offs to get the best airless spray. You dont say how you are going to apply it but I guess it will be by brush. If so how is the top coat going to brush out? These comments come from a number of years where I was technical manager of a team developing high performance tolerant epoxy coatings. Most of our work was tested by airless spray. We worked at controlled temps in the lab - 23degC -but obvioulsy the field trials and commercial jobs showed the performance over a wide range of temps and condition. Just recently we bought this new (15year old) narrow boat and I starting to get rid of the rust spots over the topsides (via Fertan, primer, undercoat and top coat). The topcoat is a traditional one pack gloss - but painting today- it was a right pain to get it flow properly to get rid of brush marks. 10 mins of sun and the roof of the boat is over 50degC!!! Paint is not formulated to be brush applied at that temp. I would be a bit nervous of buying an industrial coating that is likely mostly applied via airless spray IF you are going to brush in poor conditions. Note also it is not just temperature that will affect the brush marks, but also high winds - which we have had yesterday and today.

I remember a post a week or so ago with the poster saying he got up at 5am and painted before the boat got too hot. That is a great idea particularly if you want to avoid brush marks. If you do go ahead then try burshing it on to an area where it is not too critical and work out the best quantity of thinner and technique to get the perfect flow.

When I get my boat repainted, I am going to get it done by an expert - in a controlled environment at the right temp.

The primer is liklely to be ok for flow.

Another issue on the top coat is that it is a 2 pack system so again  it is likely to be less forgiving if you are brushing - although they are quoting pot lives of 10 hrs which is very long compared to some 2 pack epoxies. If you are doing fiddly stuff then you dont want to mix up a lot of material so that means you need some way of measuring reasonably accurately the amount of one part to the other. In the data sheet for the top coat it does mention thinning to be able to brush apply so make sure you have the right thinner. A 2 pack epoxy is going to cure much much faster at higher temps so that may mean brush marks dont flow out well enough at high roof temps. As a guide, chemical reactions go twice as fast per 10degC rise so if it is optimised for 20 deg C, if applied to a surface at 50degC then it will cure 8 times faster - the upside of this is that there is no danger of undercure. (For those of you challenged with maths - if the cure is 10hrs at 20deg C, it will be 5hrs at 30degC, 2.5hrs at 40deg C and 1.25hrs at 50degC) - this is the crosslinking reaction .....not the drying time which is a function of the cure rate AND the evaporation of any solvent.

What colour is your roof? Ours is dark blue - hence the high temp in the sun.

To comment on Tony's points,

I would not worry too much about porosity. All coatings are porous to some extent and epoxies are the best. This will be a modified epoxy (ie something built in to give it the surface tolerance) but this is unlikely to degrade porosity much. You are not going to get better. Asking the supplier for porosity info will  not help. They will not be able to give you an answer that you can compare to anything. It is not however advertised as being a submersible coating so will not be as good as 'bog standard' 2 pack epoxies for submersion duty.

Apologies for the ramble......you did ask!

Shelf life will be an issue but typically epoxies last 2-5 years if stored properly. The data sheet actually says minimum 24 months but do follow the storage temp instructions. The can of top coat I opened today (a one pack) was 8 years old (still sealed from new) so conventional paints do last a lot longer.

Please let me know how you get on. I would certainly be interested in trying the primer on areas of the boat that dont need the 'perfect' finish.

[Alex Cat]

Really, really interesting.
I actually quoted some of your post back to my first contact with the chap who is importing/using the paint.

Be curious to hear what he says about your concerns re. application etc.

 

And not a ramble at all - really appreciative of you taking your time to post so comprehensively.

[Dr Bob]

1 hour ago, Alex Cat said:

I actually quoted some of your post back to my first contact with the chap who is importing/using the paint.

 

 

 

If the chap is importing and using the paint, then he should be able to advise the best thinner levels and technique to avoid brush marks over a range of temperatures. That would be very useful info.

Best of luck and let us know how you get on.

[Boat&Bikes]

3 hours ago, Alex Cat said:

Really, really interesting.
I actually quoted some of your post back to my first contact with the chap who is importing/using the paint.

Be curious to hear what he says about your concerns re. application etc.

 

And not a ramble at all - really appreciative of you taking your time to post so comprehensively.

Importing from Scotland? Anyway Chemco are are very reputable company with a very good reputation. 

[Phil Grierson]

Morning All, I'm a new member so please treat me gently in any replies.

I've been reading the various posts on protective coatings with some interest and for the sake of openness, Firstly, I want to declare that I am a distributor of specialist marine and industrial coatings. Secondly I notice that there is a fair amount of confusion around paint, what to use and where to use it. Chemco offer good quality paints (we don't deal with them but I know their reputation).

For starters there are a number of issues that should be considered before deciding which paint to use; where is the paint going to be used? what preparation are you willing/can afford to do? what is the substrate (and its not just as easy as GRP or Steel, you should also consider non ferrous and galvanised substrates), how is the coating going to be applied, (brush/ roller/ HVLP spray, Airless spray), is the coating exposed to UV, where are you going to undertake the application, (covered building or in the yard). All these and more need to be considered if you are going to match your situation with the right product. Also be flexible; you may need to change one or two of your perimeters to achieve the best result. 

Once you have all the information to hand then you can make an informed decision. For example unprotected epoxy exposed to UV will chalk, darker colours will show this more than lighter colours but the UV is still breaking down a few microns of paint every year. If you intend to spray apply polyurethanes (PU's), either single or twin pack, they contain isocyanates as their curing mechanism and these are carcinogenic, so it is not just you you need to worry about if in a non controlled environment. Some epoxies are rated for full immersion and some are not, if you are putting an epoxy on or below the water line, make sure you choose one that is rated for full immersion. You also need to check that the particular coating you choose is surface tolerant and/or moisture tolerant. Surface tolerant means that it is tolerant of a lower level of preparation standard and moisture tolerant means that it will tolerate damp (but not running water). The Chemco photo showing their product being applied on to a surface with beaded water is marketing hype; never apply a moisture tolerant coating in such wet conditions, you would always wipe the surface down so that it is what is known as matt damp. If using a single pack paint above the water line you should figure out if the paint has some resistance against 'ponded' water, i.e. in areas where water can puddle be careful, some single packs have reasonable resistance some don't and the paint will blister and peel. In bilge tanks on steel boats you do need to be very careful of something called sulphate reducing bacteria (SRB'S). This is where a bacteria actually causes significant corrosion. Some epoxies are resistant to SRB's some are not so resistant. Finally not all coatings contain active anti corrosive pigments, some are simply barrier coatings meaning that if you take away any one one of moisture, oxygen getting to the iron in the substrate you won't get corrosion. However as Dr Bod has said all coatings are porous to some extent. 

Sorry if I'm boring anyone but the long and the short of it is, know and understand what you want to achieve and speak to a specialist distributor. If you speak to a manufacturer they will only be able to tell you about their offering, a distributor will be able to offer you coatings from many manufacturers and is likely to be able to navigate through the myriad of potential paints and coatings to give you something that will work in the perimeters you have set at a price you can afford. Remember that Epoxies are not necessarily more expensive than single packs, PU's are perfectly safe if used correctly.     

 

[Alex Cat]

Wonderful.

And in the end I have chosen someone else to do my roof who will be using more 'conventional' paints,

Any recommdations for a steel roofed NB?

No top box and not used as storage space.

Will have 2x semi-flexible solars stuck to the surface (hence wanting to ensure the roof is in tip top condition before hand).

[Phil Grierson]

Alex, in this particular situation and provided your roof has a fall, (i.e. water is not likely to pond) and no storage or foot traffic, it would seem that a single pack product along the lines of Sigmarine 48 or Corroless RF16 would be fine as a finish coat. To Prime the rusty areas I'd recommend a compatible Zinc phosphate primer such as Sigmafast 20 or one of the Corroless Primers such as Corroless S. Hempel, Jotun and Sherwin Williams are also well known in the marine world

Corroless RF16 - 2015.pdf

Corroless S - 2015.pdf

SigmaFast 20 [7155].pdf

Sigmarine 48 [7238].pdf

The only thing I would be a little concerned with is the glue that you are sticking your solars down with and whether the solars could trap moisture underneath them.