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Author Topic: Varnish  (Read 2301 times)

Paragon

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Varnish
« on: January 23, 2017, 11:45:33 PM »

hi all .
I know I have read it somewhere on here but I can't find the posts now that I need it .
Can anyone recommend a easily sourced Waterproof varnish that will not react with halfords primers and other acrylic paints .
 I have ronseal interior varnish but I'm not 100% sure if it will be waterproof.
I used yacht varnish previously and it reacted with the primer when it was sprayed over it .




Thanks


John
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Howard

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Re: Varnish
« Reply #1 on: January 24, 2017, 12:19:07 AM »

Hi, John,
 I always use Ronseal exterior polyurethane brushed on never had a problem  the interior is water based quick drying
 and been told it will turn milky white if in the water to long. theres a great guy on here called Dave (stavros) he's the man to ask  as what he don't know about painting you can write on the back of a postage stamp.


                               Regards Howard.
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roycv

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Re: Varnish
« Reply #2 on: January 24, 2017, 01:07:09 AM »

Hi all, as the subject is varnish I went to buy a tin from a DIY store and asked for a durable one.  I was shown what was a water based one and bought it, milky white.  Seems to work OK.

BUT I asked the young man,who showed me where it located, about the old type varnishes (yacht varnish) and he said they were unavailable but things may change in the future as we come out of the EU and can go back to spirit based ones.
Anyone care to comment?
regards Roy
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derekwarner

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Re: Varnish
« Reply #3 on: January 24, 2017, 01:59:42 AM »

Roy

The following link for a French varnish by the name of Le Tonkinois...it  is reported to be the best [superior to all others] natural varnish with no added chemicals or growth hormones :o ......naturally totally different to two pack epoxy sealers of any chemical rendition of a clear finish

A good read is the use of TUNG oil [as used by the Chinese in 400 BC to water proof timber vessels], then finished with Le Tonkinois varnish :-))  a finish......good enough to :kiss:

Will be a ......beautifuld day for a Angus OZ Beef pie & a beer at Ettalong beach for Australia Day this Thursday the 26th...please convey our MBM members best wishes to your host for your stay [father & son...gone sailing {-)]

Derek



https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=0ahUKEwiM3vu60tnRAhWGnpQKHbbaD7UQFghYMAk&url=https%3A%2F%2Fwww.svb24.com%2Fen%2Fle-tonkinois-marine-n01-boat-varnish.html&usg=AFQjCNFDT2TVtvyZRxHtAge9q-kMYrKagw
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Derek Warner

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www.ils.org.au

Colin Bishop

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Re: Varnish
« Reply #4 on: January 24, 2017, 10:25:15 AM »

Roy, your young man has gravely misled you! The solvent type polyurethane varnishes and traditional yacht varnish are still readily available in small tins although not always stocked by the main DiY stores. Ronseal, Blackfriar, Rustins and Wilko are the main brands. Local hardware stores are the most likely stockists.

The water based acrylic stuff you have has two main potential drawbacks:

It tends to be water resistant rather than waterproof and, as Howard has already said, if immersed in water has a tendency to bloom from water absorption.

It does not always bond well to the surface to which it is applied. Probably OK over a matching primer but not over something like an enamel or car paint topcoat where it can just constitute a film covering. As it is soft, it is only a matter of time before you get a knock or abrasion and then it will start to peel off. Been there, done that!

Yacht varnish is intended for use on timber finishes and not as a top coat to a painted surface. It is a flexible covering intended to allow for movement of the wood and has a pronounced yellowish tint which will alter any underlying colour.

Interior polyurethane is the best to use as it is more transparent than the external variety which includes UV filters which also give it a slight tint. I have never known it react with anything it is applied to as long as the surface is fully dry.

Colin
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Paragon

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Re: Varnish
« Reply #5 on: January 24, 2017, 11:52:26 AM »

Thanks for the replies.
Colin in a nutshell I'm needing to buy  interior polyurethane varnish?
And this should be ok to use over existing yacht varnish and to use Halfords primer over or on top of without reacting?




John
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Colin Bishop

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Re: Varnish
« Reply #6 on: January 24, 2017, 12:24:27 PM »

Not totally sure what you are saying there John but if I understand you correctly:

Yes, you can use polyurethane over Halford's primer as long as the primer is fully dry. You wouldn't need to use primer over polyurethane as the varnish is always a top coat.

It's probably OK to use the polyurethane over old rubbed down yacht varnish but it would be better to use more yacht varnish really as yacht varnish is slightly flexible and there is a possibility of the polyurethane cracking. Plus yacht varnish is intended to be applied on top of yacht varnish (after rubbing down of course)

Colin
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Paragon

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Re: Varnish
« Reply #7 on: January 24, 2017, 12:46:42 PM »

I used a test piece for the job I'm doing and the primer reacted with the yacht varnish , where I'm spraying there will be an overlap as the hull has had varnish applied prior to the painting below the waterline. That's why I'm asking and doing some tests .
I didn't think the yacht varnish and Halfords primer would react , unless there is something else going on in there . 
I'll keep trying .


Thanks. John


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Colin Bishop

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Re: Varnish
« Reply #8 on: January 24, 2017, 01:01:54 PM »

Yacht varnish is inherently a bit soft, not the same as polyurethane. The Halfords primer contains a solvent which will almost certainly react with the yacht varnish. Ideally you should rub down and remove the yacht varnish below the waterline.

Yacht varnish is not intended to have anything on top of it except more yacht varnish I'm afraid. You might get away with rubbing it down when it is fully dry to provide a keyed surface and then using a brush on all purpose primer that doesn't contain a solvent. Not good practice but may work.

As you will have realised by now, mixing and matching different types of finish is a bit of a minefield.

Colin
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Paragon

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Re: Varnish
« Reply #9 on: January 24, 2017, 01:36:34 PM »

Thanks Colin , yes this can be a mine field ! It only reacted in a few places on my test piece but enough to raise alarm.
I'll rub below the waterline down and maybe airbrush an acrylic primer on in the hope that without the solvent there will be no reaction, and possibly this will create a barrier for a light coat of Halfords red oxide primer .
Really I just want to use Halfords red oxide primer as a anti foul colour .


These things are sent to try us !!


Thanks Colin .
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Colin Bishop

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Re: Varnish
« Reply #10 on: January 24, 2017, 01:58:48 PM »

I have successfully used Halfords primer over other finishes when necessity dictated! The secret is to spray with very light coats so that the solvent evaporates almost as soon as it reaches the surface and doesn't have the chance to react with the existing coating. Just a light dusting at first, takes a bit longer but worth the extra time. Again, not good practice but sometimes needs must...

Colin
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Paragon

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Re: Varnish
« Reply #11 on: January 24, 2017, 02:54:23 PM »

That could be the issue Colin as it was ok on 90% of what I tested on .
I'll try that .
Many thanks once again!


John
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Paragon

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Re: Varnish
« Reply #12 on: January 25, 2017, 08:09:21 AM »

Colin I applied a few dry coats of primer last night and had no reaction with the varnish although I did give it a good rub down before hand. I'm hoping I'll have no bother now when it comes to applying varnish as a top coat later on .
Would be nice to get a good acrylic primer that I can apply with the airbrush, I have Vallego primer but it doesn't rub down very well , very soft .


John
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Colin Bishop

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Re: Varnish
« Reply #13 on: January 25, 2017, 08:12:50 AM »

Hopefully you have got it sorted then John!


Colin
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Paragon

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Re: Varnish
« Reply #14 on: January 25, 2017, 08:30:31 AM »

I hope so Colin, I applied really fine dry coats of the primer and I'll do the same this evening.
I imagine I'll have no bother applying the varnish over the top of the primer??


John
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Colin Bishop

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Re: Varnish
« Reply #15 on: January 25, 2017, 08:55:12 AM »

No, you shouldn't but leave it at least 24 hours or longer ar room temperature.

Nothing is guaranteed!

Colin
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Paragon

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Re: Varnish
« Reply #16 on: January 25, 2017, 08:59:39 AM »

Yes it won't be rushed but I'll also do a test on a piece of ply before .
Varnish would be a coating I have used very often on models , all my others are coloured . New territory for me .


Thanks


John
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