paint problems

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viramati

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my much loved Freeman 26 (bought in may) was painted last winter with 'Marine & industrial' 2 pack urethane gloss. in the last 2 weeks it has started to come out with little bubbles all over the superstructure (spreading like cance) and they seem to come up as you are looking!! would appear to be a total disaster. any ideas?
 
If it had previously been painted then it sounds as though it may have been with a single component paint. You cannot use a two pack poly on top of a single component paint!

Alternatively it may have been applied to an old weathered and porous gel coat with out the necessary sealing with an epoxy primer and appropriate undercoat.

Either way it's a strip off and start again job I would guess.
 
Looks like I'm well and truly in the s***t. I bought the boat (1964 freeman 26) as fully restored paying top dollar and she does look lovely or at least she did until a few weeks ago. The cost of doing the work would be frightening for a boat of its age and now probable value. The chances of getting anywhere with previous owner are very slight (brought it through boat-showrooms who are just the brokers). Friend who has been around boats for a long time suggest waiting 6 months to a year let it settle down then heavy sand and repaint!!
 
[ QUOTE ]
You cannot use a two pack poly on top of a single component paint!
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[/ QUOTE ]

As far as I'm aware it's the other way round, you can't put a single pack paint over a two pack poly
 
I agree with your friend. If it was painted last winter and only now showing a problem I don't think it's a compatibility issue. Only thing I can think is a porous gelcoat that allowed solvents from the paint to go in and that is now appearing in the form of blisters but it seems strange there has been such a time lag.
My inclination would be to live with the problem for a while and see how it develops. It might look bad but it's probably only cosmetic. When all the activity stops sand it all down and look carefully for pinholes. Fill with a fine filler and repaint.
It would be worth coming back to the forum when you sand down with your findings
 
Generally you can put a single pack over a 2 pack but not a 2 pack over a single pack. As always there are exceptions but not many.
 
Thanks Pasarell. I think you may be right. I don’t think it was previously painted (will try to find out) but being 1964 the gel coat was probably in quite a state. Paint also seems quite soft in areas so was wondering if it could be a hardener problem. It must have been painted at least 7-9 months ago so you’re saying a compatibility problem would have shown up a lot earlier.
 
Ind / Marine coatings can be different from dedicated yacht products and might not be suitable for GRP structures
Sounds to me like the gelcoat has not been sealed and there has been solvent retention
The pinhead blisters are caused by the retained solvent expanding and trying to escape
As the paint film is thinner than the GRP the pressure exerted by the expanded solvent forms these tiny blisters between GRP and Poly paint film they can come and go but repaint is the only way to eradicate them
On topsides they are normally only cosmetic but never the less un sitely The "cure" would be to leave for a while apply several thin coats of a two pack primer (International's EGA 088/089 used to be a favourite in the prof world) insuring that temperature and drying times are adhered to, then overcoat with a dedicated Yacht two pack finish or one pack poly
 
Compatibility problems normally show up pretty much immediately. I did wonder about hardness (and curing agent) but didn't go there as you hadn't mentioned it. Even so it seems strange the blisters didn't appear earlier. You could try rubbing with a cloth soaked in the solvent for the paint used. If the paint comes off on the cloth it hasn't cured properly. If it was a 2 pack polyurethane you should be able to use International Thinner No9 if it's easier to get.
 
I think you could be right Grajan but do find it strange that the blisters didn't appear sooner. It was painted last year and normally the blisters would appear when the weather warms up if it's a simple case of solvent coming out, not wait until it is cooling down at the end of the year.
I really don't think EGA 088/089 would be a good idea. I'm assuming the paint is a 2 pack poly but it could also be an acrylic. Putting an epoxy over either would not be great and could well lead to bigger problems.
I think Viramati should investigate more before any firm plan is offered.
 
Soft paint could be down to undercure, bad mixing of the product, a temperature drop after application, moisture retention within the GRP Solvent droplets in the atmosphere
it is a minefield when painting GRP with two pack!
 
G'day Viramati,

I suspect this may be a failure due to faulty curing caused by conditions at the time of coating or poor mixing, or even failure to let the mix stand prior to application, some 2 pot paints must be left foe some time after mixing to let the chemical reaction start.

I would think if it was a problem with the substrate it would be peeling or cracking not pin holing.

Try contacting a local marine paint sales rep and get them to have a look at it, they will be able to determine the cause of the problem. The fact that some areas are soft is a good indication the mixing may be a problem.

Please let us know how you get on; if it's more than a week away please respond with a new post as this one will be well down the list.

Hope this helps, good luck.

Andavagoodweekend......
 
Not surprised with time lag have seen it take longer can be caused by solvent /moisture mixture (wet season?)
Strictly speaking the present coating would need to be removed unless overcoating with a single pack but if it has been a catalyst problem and is only abraded it could happen again as there could be what look like sound areas now but could blister in years to come
EGA is a two pack steel shop primer but when used on GRP can be an exellent sealer coat
 
Agree with some responses.

a) It is unlikely to be a reaction after this time

b) The change in atmospheric conditions makes me think it's a water problem getting behind the new coating.

c) Whatever, you need to strip right back and start again with a barrier coat primer. Or live with it. Just don't overcoat it again.
 
Without seeing /sniffing/sampling the problem we could make suggestions all night
My 25 years in the Yacht Marine Paint Industry taught me never to be surprised with the results of analysis when dealing with this type of problem!!
 
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