Varnish

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Ed
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Re: Varnish

Post by Ed »

Do you know what the varnish is that is currently on the decks?

It looks like a proper varnish, rather than a two-pack, but I might be wrong....and it doesn't look too thick. It isn't a 'killer' issue, but it would be useful to know what it was.

OK, first thing is that this does not look like so much damage that you couldn't get away (at least for a while) with a fix'n'patch approach.

It all depends on how long you want to have the boat....and how long you want it to last, but there are a finite amount of times you can strip varnish before you start to damage the veneer and you start thinking about a re-deck. When the condition is like this, I would normally suggest patching and keeping going for a few more years before doing a complete re-strip.

There are some provisoes for this. First: If the current varnish is a soft one-pack, then it will be easier to remove and you will do less damage to the wood, so going for the full strip is not such an isue. But on the other hand, it will also be easier to patch in the repaired varnish bits. So if you decide to remove or patch, it is easier to do it over single-pack than a full poly 2 pack.

If the original varnish is one-pack, then you 'should' really only use one-pack to patch it in. If the original was two-pack, then you can use single or two pack to patch in. But this is not always the case! It depends on the diluent used in the covering coat and whether it attacks the previous coat. some do and some don't, but best practice is to not do it.

Some two-packs/polys/epoxy are very hard to patch in, whereas singlepacks are very easy indeed. They are hard for a number of reasons. first if you are not careful you sand too much wood off when trying to feather the edges, which may damage the wood and may lead to wood being less oxidised/faded.

Also some 2-packs can be very uncoloured in the can (like water or light straw coloured) but make the wood much darker in colour, whereas single packs can be very red/purple/orange/brown in the can, but simply give a golden colour.

Some 2-packs are less UV safe than they should be (Bondamarine G4 does this too), which means they yellow on the boat, and when you try and patch them it is impossible to get the colour the same.

So, this is all a long way of saying: Patching may work. Patching a singlepack varnish is easy and tends to not be problematic....but it is also easier to remove. Patching a hard varnish, may be harder and more problematic, but the work taken to remove it all is much more arduous and much more likely to damage the wood.

Hence, my asking what the varnish was! In this case, even if it is a hard double-pack, it does not look too thick, or faded and I would try patching first.

But OK.....you want to remove it....you can afford the money for sandpaper/varnish etc and you have twice as much time as you thought you originally needed. In the end, this will be the preffered choice anyway :-)

My approach is this:

Stage One:
Get a good hotair gun, with adjustable temp (and power?)
http://www.screwfix.com/p/dewalt-d26411 ... tAodygsAaQ
and a good scraper with metal handle. which means this one:
http://www.powertoolsdirect.com/stanley ... de-scraper. You will need a couple of blades, but you won't have to sharpen it, which means you are much less likely to get a sharp corner and dig it in.

Only work with the grain. Don't burn the wood! Work out exactly the right temp to remove the varnish but not damage the wood in any way. this is lower for one pack than two.....although most epoxy comes off with surprisingly little heat.

Work with care and start somewhere not so obvious to get the feeling for it.

Remove all surface varnish or as much as possible, but don't gouge or scrape the veneer.

Stage Two:
Find some real varnish stripper if you can....or put up with the cost and inefficiency of the new safe stuff.
Go back and strip everything again, making sure you get down to the top of veneer, with the Stanley scraper.

You might need to do this a few times. it depends on the grain of the wood. If it is very close, you won't need to do it too much, but if it is open, you will need to scrub it with some brass wool or an dishwashing pad. When finished wash it down with something that will neutralise the stripper. Meths used to be recommended. Personally, I reckon lots of water and a good detergent does it better than anything else. then if its winter, dry it. I have had mould appear very quickly on decks if not dried.

Stage Three

Sand it very gently with grain and/or use a good quality and sharp cabinet scraper. Which works best will depend on the veneer and the depth of grain. By now there should be no sign of any old varnish left. this stage can take ages and costs lots of money due to the volume of sandpaper you use. Can you use a sanding machine? Maybe....a good random orbital, but not anything else. I tend not to....the chance of damage is just so high and they are horrible and noisy to use. Long sanding boards? Great for painted hulls, but not appropriate for decks, sorry. When you finish everythign should be a constant matt colour. If their are colour shifts, you might have a problem due to wood fading and/or over sanding.

this is the only stage where you have to remove some wood....so just do it carefully. You can only do this so many times, before you go through the veneer alltogether.

Stage Four

If required.....you might want to: wash again with a wood restorer or renavator (sp?). I have had some sucsess and some disasters with them. Use Oxalic acid on stains. I tend to not do this as I prefer black marks to grey marks, but others have had sucssess.

At this stage, I often give it another really good wash, with a scrubbing brush and carpet detergent, you will be amazed by now much dirt still comes up. Then dry it really well.

As for varnishing...... that is whole other story....and I am getting close to end of lunch break, so search our archives....or look here: http://www.cvrda.org/boats/hintstips/va ... h_menu.htm

As for what varnish, it really depends on so many things, not least of all how long you intend to wait before you come back to do it again.

2pack varnish lasts longer but is harder to remove
1pack varnish needs replacing more often but is easier to do.

my preference - personally, but this will only start a flaming war....is singlepack varnish over hard primers.

So for a racing boat/topdecks:

Primer: Bondamarine G4 or if there is any left anywhere....Blakes woodseal/International UCP

Building coats: A simple Alkoid varnish: Jotun Spontan or standard Blakes/int singlepack....or I guess Epiphanes if you can afford it.

Topcoat: Epiphanes.....just cos its simply the best, strongest and easiest

for a working boat, I would most probably just use Jotun Revalak as primer through topcoat, but might be tempted by a first coat with G4.

If you decide to go down the G4 route......their are pros and cons.....search archive or ask again.

good luck

looks beautiful

eib
Ed Bremner
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chrismartin3583
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Re: Varnish

Post by chrismartin3583 »

Blatent business plug but.......

We have started to use products from Skippers.

The one pot Topkapi is as good as Epifanes.

The two pack poliglass is an incredible product, 6 coats on in a day. Very reminiscent of the "old" Blakes cyano based one pack varnish. It's not all that hard though, so for the top finish we use Acriglass, which doesn't dry as fast but is a harder finish.

I don't know of anyone retailing these products, but i'd be happy to supply.
High Flow
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Re: Varnish

Post by High Flow »

wow,
thanks for the very detailed answer.
I'll have to check back with the previous owner but as far as I know they used a 2-pack varnish.
thanks 1000times
High Flow
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Re: Varnish

Post by High Flow »

what do you mean by patching?
Remove the existing varnish only in patches, or don't remove it at all and just sand and apply the new coating?
The general idea is to keep the boat for as long as possible, or forever!
So making sure not to damage the wood is very important!
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Ed
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Re: Varnish

Post by Ed »

patching would be just removing any varnish which is damaged or lost adhesion to the wood and just varnishing those patches.

The patches could be big or small, but the idea is to remove as little as possible, whilst removing anything that is in any way compromised.

cheers

eib
Ed Bremner
CVRDA


Jollyboat J3
Firefly F2942
IC GBR314 ex S51 - 1970 Slurp
MR 638 - Please come and take it away
Phelps Scull
Bathurst Whiff - looking for someone to love it
High Flow
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Re: Varnish

Post by High Flow »

what about the transition from the patched areas and the old varnish? How can I hide them? To I add one or two coats to the whole deck ontop of everything?
Thanks
max
Rupert
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Re: Varnish

Post by Rupert »

The basic answer is you can't hide the join. The wood and the varnish will be different colours. To get a uniform look, you do need to strip the whole boat. To get sailing, or to tide you over until the weather is good for varnishing, patching works OK.
Rupert
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Ed
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Re: Varnish

Post by Ed »

I think it depends....

Sometimes, especially if the varnish was a golden single-pack...and there is not too much fading of the wood, you can certainly patch in and I don't think you will see the difference....well you may if you know it is there and look for it, but it needn't be too offensive. On my Tideway, I have often stripped back bits where the varnish has failed or there has been damage and patched in. This worked for many years with next to no obvious patching at all. I agree now it is looking patchy, but this has mainly been due to the mixture of G4/Tonkinoil/Ravilak varnishes all over the place.

I agree it is harder if the wood has faded, or the varnish is a twin pack....or unknown.....or it is a large area to be done in a very obvious place, like across the decks.

For sure it does not always work. The decks on my Jollyboat were patched in and they look a right mess, didn't work at all. FWIW, this was due to using G4 as primer and first few coats. It fades and is very hard to patch in. But honestly, if it had been Ravilak, it would of been fine. IMHO, G4 is a good primer, but not that good a varnish, due simply to the lack of UV stablisers. I don't like the way it builds up....but it is still a good primer.

but....

go back and look at those images again. Do you really think it is worth stripping the whole boat down to fix up those small bits of damage, most of them are simply areas of wear & tear and this kind of damage happens most years on any old wooden boat and it can't be worthwhile doing a complete re-varnish every year??

eib
Ed Bremner
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Jollyboat J3
Firefly F2942
IC GBR314 ex S51 - 1970 Slurp
MR 638 - Please come and take it away
Phelps Scull
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Rupert
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Re: Varnish

Post by Rupert »

Going back and looking at the pics - no, I wouldn't strip it back.
Rupert
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PeterV
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Re: Varnish

Post by PeterV »

I seem to have sorted my problems. I scrubbed it all with sugar soap to start with, then I rubbed it down very hard with coarse wet and dry, then scrubbed it with sugar soap again the rubbed it down hard a couple more times with w&d. I've now put 2 very thin coats of Original varnish on it and its looking a great deal better. I was amazed how much varnish was on there, with all the rubbing down I've still got nowhere near the base layers!
PeterV
Finn K197 & GBR564
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Ed
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Re: Varnish

Post by Ed »

Glad to hear it,

look forwards to seeing it.

cheers

eib
Ed Bremner
CVRDA


Jollyboat J3
Firefly F2942
IC GBR314 ex S51 - 1970 Slurp
MR 638 - Please come and take it away
Phelps Scull
Bathurst Whiff - looking for someone to love it
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JB9
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Re: Varnish

Post by JB9 »

If anybody is looking for an economic yacht varnish then try Screwfix. Their own brand seems to work very well.
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