G4 Thoughts

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Mark Jones
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G4 Thoughts

Post by Mark Jones » Sun Apr 22, 2012 6:33 pm

Have not posted for a long time but,would welcome all thoughts on the following.
Old wooden working boat exposed to UV etc for about 9 months each year. varnish needs stripping right back.
So I am thinking on 2 coats of G4. I do not remember putting varnish over G4 when I used it on the Dolphin, reasons to varnish?
Any other ideas?

Cheers
Mark

Will be posting lots more Qs soon but want to keep subjects seperate

Rupert
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Re: G4 Thoughts

Post by Rupert » Sun Apr 22, 2012 6:49 pm

G4 supposedly isn't very UV resistant, but a boat which is covered most of the time doen't have a problem. If your's is out, it might be worth looking at alternatives. Bondaseal has been mentioned in the past, but I've not used it.
Rupert

roger
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Re: G4 Thoughts

Post by roger » Mon Apr 23, 2012 8:44 am

I know Chris used G4 on Terrapin when he restored her and she was supposed to be varnished but the owner at the time never got round to it. She has now been varnised I belive but I dont think there was a problem.

My Hornet has had the decks done with G4 and then varnised, no problems but she does spend a lot of time under cover.
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kfz
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Re: G4 Thoughts

Post by kfz » Mon Apr 23, 2012 9:09 am

For the price of a tin of varnish is not just worth doing it, You know the Varnish is UV resistant? Plus it goes quite far really over G4 so it would take many coats i wouldnt expect. and it looks nice.

Be interesting to see what happens if you didnt, I know there was some debate about how UV proof the G4 is.

Kev

p.s Quite sold on the G4, looking forward to see how it works out and how long it lasts.

billytwiglet
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Re: G4 Thoughts

Post by billytwiglet » Mon Apr 23, 2012 1:44 pm

Terrapin was rubbed down thoroughly and varnished with four coats of Epifanes classic varnish. The results are excellent. However, the sealer underneath had turned dark in colour which is irreversable other than by removal. The varnish has bonded strongly to the sealer, but in places it is pulling the sealer off the wood, and it will just peel off if encouraged. This is not the case where the varnish was used to prime the new wood; no problems there. At some stage, I will have to strip it all off and start again.

Personally, I would use either the manufacturer's primer, then varnish, or thinned varnish then top coats per manufacturer's instructions.

Epifanes, like many good quality varnishes, will give excellent uv protection. It also allows a rub down and recoat quite easily. I don't believe in mixing chemistries, as you would be with g4 and classic varnish. G4 doesn't breath either, it's plastic.
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roger
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Re: G4 Thoughts

Post by roger » Mon Apr 23, 2012 4:14 pm

Interesting... one of the worries was how easy would it be to take G4 off when the time came. Is it looking like it might be easy to remove or is that several years of unprotected UV degradation.
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Pat
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Re: G4 Thoughts

Post by Pat » Mon Apr 23, 2012 7:08 pm

Sandy coated Half Cut's deck with two coats of G4 only about 5 years ago to last "one season until he got round to redecking it" - which still hasn't happened! The G4 has lasted well but the deck itself was delaminating and G4 won't cure that!
(Half Cut and What a Lark Removals Ltd)

Garry R
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Re: G4 Thoughts

Post by Garry R » Mon Apr 23, 2012 8:38 pm

I used G4 inside the hull of Gannet (clinker built mahogany and ribbed interior) and was going to put varnish on top inside. Never got round to it and 5 years on am still pleased with the results. On the decks and hull she was stripped back to bare wood and had G4 applied until the finish began to "shine" with rapid coats. She was varnished with International Original BUT the G4 was given a long cure time and then well rubbed down to provide a key. I have had no problems with flaking aexcept on the floorboards which I coated with G4 and sprinkled with sand. In this case I couldn't rub down and there has been flaking of the top varnish - NOT the G4. Maybe as well I didn't put varnish inside the hull as it may not have stuck well as it would be really difficult to get a key under the ribs. Perhaps a good idea would be to use varnish inside on a ribbed boat but OK on a ply boat inside. So I guess the bottom line is - great on bare wood and ensure a good key for the varnish when G4 has cured.

PS She always has a cover on when stored so I really dont have UV issues with inside the hull or the decks and no flaking of varnish on the outside of the hull where well keyed - hope this helps.

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Re: G4 Thoughts

Post by Keith66 » Tue Apr 24, 2012 11:56 pm

G4 is a polyurethane pond & concrete sealer, its only use near boats is to seal one shot MDF moulds when fibreglassing.
As a varnish it is utter crap. Oil based varnishes last longer & are easier to refinish, Epifanes is one of the best.

Stephen Hawkins
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Re: G4 Thoughts

Post by Stephen Hawkins » Wed Apr 25, 2012 8:25 am

That is not everyone else's experience, including my own.

You can put three coats of G4 on a boat in a day - that in itself, for someone who has to work outside in the UK, has significant value.

Not only that, but how much is a can of Epithanes and how far does it go?

Cheers
Steve Hawkins

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roger
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Re: G4 Thoughts

Post by roger » Wed Apr 25, 2012 8:42 am

Have to say I have no complaints with G4. Put onto bare wood in 2005 and varnished over the top and no issues. The finish was good enough to win the concourse at Bosham last year.

Would I use it again.....? Probably yes as Steve says three coats in a day.

I also understand that G4 was originally developed for the marine industry and then found to be a good pond sealer.
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chris
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Re: G4 Thoughts

Post by chris » Wed Apr 25, 2012 8:51 am

I recently noticed in a chandlers that Bondaseal are selling G4 marine again. This is marketed specifically for marine use.

kfz
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Re: G4 Thoughts

Post by kfz » Wed Apr 25, 2012 9:10 am

Is G4 not a replacement for Epoxy or maybe primers in some instances rather than a replacement for varnish? Im most pleased with the G4-Schooner finish. The only problems Ive come across with G4 is that it melts yogout pots and the screw on lid likes to glue on.

PersonallyIve only used it where I specifilly want the imprermable sealant properties but I dont want to use epoxy for the many disadvantages.

Kev

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Ed
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Re: G4 Thoughts

Post by Ed » Wed Apr 25, 2012 9:59 am

I think that I have had more problems with it than most people....

but would most probably consider using it again, but mainly as a primer. I certainly don't like the idea of not over-coating it with a proper varnish for uv protection.

I wouldn't see it as a replacement for epoxy (which generally I don't like, although do use diluted occasionally as a primer), but as a replacement for Blakes Woodseal or UCP as a primer.

However, there is no doubt at all that it works.....and works very well too.

cheers

eib
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Ed
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Re: G4 Thoughts

Post by Ed » Wed Apr 25, 2012 10:07 am

This is marketed specifically for marine use.
yes....I think the key thing is that it is 'marketed' for marine use rather than being anything different.

I talked once to a Bondamarine salesman and he was quite adamant that all their products from the DampSeal to the Bondamarine Wood-hardener are basically the same product....but have different amounts of diluent and differing 'additives'. If I remember correctly, the 'marine' one had some UV-protection additives and the wood-hardener just had more diluent.

I wouldn't buy it from a chandler though.....it's much cheaper bought 5Kg at a time from a larger supplier like CFS, which I think has it at around £45.

cheers

eib
Ed Bremner
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