Paint advice - G4

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Rich
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Paint advice - G4

Post by Rich » Thu May 01, 2008 6:16 pm

The time is fast approaching when I have to paint the hull of the Phantom I'm restoring. Though I have taken it back to bare wood I had not planned to spend lots on expensive marine paints or epoxy's. My original idea was:-

2 coats Screwfix Universal White primer
2 coats Dulux Undercoat
2 coats International 10yr Exterior gloss

However I was now considering whether to first apply 2 coats of G4 pond sealer and reduce the primer and undercoat to one coat of each. Having never used G4 before, I was wondering if it would be suitable to seal a hull and also how easy it would be to flat it to a good smooth finish before adding the paint coats. Also I've no idea how much to buy, would 1kg of G4 be sufficient for 2 coats on the hull of a Phantom?

Cheers
Rich

Garry R

Re: Paint advice - G4

Post by Garry R » Thu May 01, 2008 6:49 pm

Answer is I'm not sure about using G4 as a general sealer before paint. Varnish - yes. You need a good rub down between the G4 and varnish with wet and dry as there is something of an oily feel to it but whether this stops good adhesion I don't know - just have never taken the risk. My feeling on all these things is that having spent ages with the rubbing down and restoration it pays to spend a little more on the correct stuff - I got International polyurethane white one pack and it gave a superb finish on a centreboard and was very tough. For all over varnish on the Firefly (hull inside and out, decks) I think I used about 2.5litres and that was 3 coats in rapid succession. Just my tuppence worth.

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Ed
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Re: Paint advice - G4

Post by Ed » Thu May 01, 2008 10:26 pm

I don't know either.....although initial impressions are good.

but ask me in a few months and I might be able to tell you.

I have only used G4 on one thing so far and that was just as a primer on a new canoe seat, which I then coated with a two-pack paint. No undercoat, no primer, just G4 and then topcoat. That seemed to go just fine. In fact it seems like a bit of a wonder-material. It seems to have an incredibly high build, it is easy enough to use, good adhesion so far, dries fast, sands well.

So far I really like it.

I have only one worry.....but it is a biggish one.

And I would love to know if anybody has sussed this out.

How easy is G4 to get off....and how do you do it.

I have just been stripping the Jollyboat which was varnished with traditional varnish and it is just so easy to take off. A little heat, followed by a little nitromors and its off.

But having tried recently to remove some polyurethanes....it can be a nightmare that gives you little chance of taking it off without destroying the wood underneath.

So has anyone done any testing on removing G4? How easy is it? What is the best method?

It might sound defeatist to be thinking of how to remove it before you even put it on, but some boats I have already had to strip at least twice and may have to strip them again before I pass them on to the care of their next owner.

So....any thoughts.

G4 seems almost too good to be true.

eib
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roger
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Re: Paint advice - G4

Post by roger » Fri May 02, 2008 8:20 am

Chris can probably tell you more but I know Merlin 36 has ahd two coats of G4 and nothing else. It still looks very good and it must be 3 or 4 years now. As for removing it Ed I dont know 36 was the first boat I know of that it was used on.

Amounts needed ? I used about 1.5 cans(not sure of kgs but I think they are 1 kg cans) on Shoestrings varnished deck and there is a lot of wood.
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Rupert
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Re: Paint advice - G4

Post by Rupert » Fri May 02, 2008 1:38 pm

I put 3 coats on a Firefly deck (narrow ones) and didn't use 500ml. I too wonder about removal - best bet will be to coat a bit of gash ply, wait a week, and try and remove it using heat, chemicals etc and see what happens!
Rupert

Michael Brigg
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Re: Paint advice - G4

Post by Michael Brigg » Fri May 02, 2008 5:40 pm

Who remembers that film, "The Man in the White Suit." ?

Image

I know we've just had the local elections and there has been lots of political egg on face, but no it wasn't about Colin Bell. It was the one about a man who invents a cloth for a suit that never needed cleaning. Perfect it would seem until no one needed to buy new suits anymore and the textile industry went out of business. Then everyone hated the poor chap.

Perhaps this is G4. Perfect until something unexpected happens, like a boat steaming in on the port tack, or anything else that lets moisture into the wood. My old firefly developed leaky side tanks and the overlying wood kind of got darker. I am sure that if G4 had been used this would have created difficulties with getting the finish back after drying the tanks out.

It has always been my impression that wood should be able to "breath." perhaps this is a bit of illogical nonsense like talking about "the Goodness" in foods or taking homeopathic pills but I have a resistance to using Synthetic epoxy paint on anything that I really value or that is irreplaceable or isn't disposable. I look after patients who have the same attitude of suspicion or even downwright refusal to use any drug that is synthetic,(not natural.)

Epoxy (and G4 for that matter) is stong medicine. It works well but... don't use it unless you are sure of the long term or short serm side effects. Experiment first where it doesn't matter.
Last edited by Michael Brigg on Fri May 02, 2008 5:46 pm, edited 1 time in total.
Michael Brigg

alan williams
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Re: Paint advice - G4

Post by alan williams » Fri May 02, 2008 5:45 pm

But its bl....dy good at sealing ponds.
Al Finn424etc.

Rich
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Re: Paint advice - G4

Post by Rich » Fri May 02, 2008 7:36 pm

Thanks for all the input. P499 has not seen the water for some years and I am half expecting her to leak like a seive when she eventualy sees the wet stuff.

Part of the attraction of G4 was that it might provide a nice water tight seal to the hull, however I don't relish the thought of applying coats of G4 only to find that I still have a leaky boat, but one that is now covered with hard polyurethane that is difficult to shift for further repair.

If my local aqauatic centre stocks G4 then I certainly plan to buy a small can and do some tests on scrap ply and will report back accordingly, but at the moment I am tempted to stick to my original plan i.e 6 coats of cheap paint and get the prayer mat out.
Rich

Michael Brigg
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Re: Paint advice - G4

Post by Michael Brigg » Fri May 02, 2008 8:14 pm

My main misgiving with Epoxy finishes is what happens on application to an old surface. They work very well applied to fresh dry brand new hulls which after all are no more than wood veneer held together by epoxy resin. The wood is effectively the flexible fibre that gives flexibility and tensile strength to the hard brittle matrix that is the Epoxy.

The problem arises I believe with older aged and consequently more flexible wood. (and ply for that matter.) The epoxy in old ply has aged with the would and like an old married couple there is give and take between the two mediums. Introduce a third younger element and there is sure to be trouble! There is a disproportionate amount of movement between the old ply and the newly applied epoxy surface leading to earlier failure of this interface. Our boats are works of art and who said that Art imitates Life?

A carpenters son Himself advised against putting new skin on old bottles and so the fundamentalist might take this as a divine caveat against use of synthetic paint although I must admit that's rather stretching the point.

So, unless you have stripped right back to virgin wood I would be cautious. If it leaks however you may need to do some cutting rather than stripping and that is a skill for which I have no experience. Renewing old wood however is not I believe affected by your finish.
Michael Brigg

alan williams
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Re: Paint advice - G4

Post by alan williams » Fri May 02, 2008 9:54 pm

Joking aside G4 is great for wood as unlike epoxy it retains some flexibility. I wouls use this instead of the ordinary paint you intend using. I stated before that its great for fixing leaking ponds I know I've used it to do just that. So if you are worried about leaks it will fix that. As it is proving very durable on Merlin 36 I would not worry about that either. This stuff was originally a marine product but epoxt imparts strength as well, which is why G4 fell out of favour with the marine industry.Anyway who wants to be stripping varnish and paint off every year when they could be sailing.
Best of luck with your project Al Finn424 etc.

chris
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Re: Paint advice - G4

Post by chris » Mon May 12, 2008 10:01 am

G4 was recommended by an Oxford boatbuilder (had been storing Merlin 36) as he always uses it on traditional boat restorations.
Yes removing G4 is an unknown to me too and is an important point. But I don't think it would be worse to remove than UPC primer as it is a similar chemical I believe. It's easy to think that restoring a boat is a permanent measure. It never is. The 'next time' should be borne in mind too.

Personally I think to save a bit of money on non-marine paints will be expensive within a few years.

I would not like to use epoxy on old solid wooden boats, Apart from non flexibility the seal would have to remain absolutely 100%. if any water does get through it will never get out again. I quess g4 would be easier to remove than epoxy too.

Rich
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Re: Paint advice - G4

Post by Rich » Mon May 12, 2008 11:55 am

I have stiil not made a final decision regarding using G4. My local aquatic center only stocked 'Blagdons V8' which I believe is similar to G4, however having read the instructions on the back of the can it would only appear to be suitable for porous surfaces.

I have retaped some of the external joints and then faired them in with a mix of expoy and fairing compound and I am unsure as to whether the G4\V8 would bond to these areas. Part of the attraction of G4\V8 was to form a complete seal of the hull as I am assuming that like with epoxy, once you get water under G4 it cannot escape. My concern is that if only painting G4 on the exposed bare wood then I may get potential water ingress at the point where it meets the epoxy fairings

Any thoughts?
Rich

chris
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Re: Paint advice - G4

Post by chris » Mon May 12, 2008 1:40 pm

On a national 12 I once owned the previous person had taped many of the lands. I took it off . It's will very soon form a nice tunnel for the water to get in, travel along and so on.

Rich
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Re: Paint advice - G4

Post by Rich » Mon May 12, 2008 4:16 pm

Like most old Phantoms this boat was a home built stitch & glue job. The external joints were taped as part of the build process, I have only replaced those joints which were totaly shot. I would have extreme reservations regarding the structural integrity of the hull if all the external tapes were to be removed, especialy as access cannot be gained to strengthen the internal side of the joints. The large unsupported floor area of a Phantoms can get quite a hammering.
Rich

Pat
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Re: Paint advice - G4

Post by Pat » Mon May 12, 2008 5:53 pm

Stick to proper International undercoat - Dulux is fine for homes not boats. One of our Larks has been done with domestic paint and it's all peeling off. Sandy (a professional carpenter and decorator) also says the Dulux you buy in the sheds (B&Q etc.) is totally different from the trade Dulux from specialists like Brewers.
(Half Cut and What a Lark Removals Ltd)

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