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05-02-2019, 11:28 AM
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#1
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Newbie
City: Mansfield
Join Date: Dec 2014
Posts: 2
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Thinning Glossy Varnish
I have read to not thin the final coat of varnish. With the weather conditions I don’t see how I can get the varnish to flow and lay right unless I use a brushing thinner of 10% or less. Any assistance would be appreciated.
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05-02-2019, 11:45 AM
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#2
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Guru
City: Jacksonville
Vessel Name: Alzero
Vessel Model: Hatteras 63' CPMY
Join Date: Apr 2017
Posts: 1,548
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Heat the varnish to 150/180 degrees in a pan of water or double boiler. It will flow out beautifully, cool quickly on the workpiece and dry and harden normally.
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05-02-2019, 11:57 AM
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#3
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Guru
City: Brookline, NH
Vessel Name: Shalloway
Vessel Model: Defever 44, twin Perkins
Join Date: Sep 2013
Posts: 2,260
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Quote:
Originally Posted by My Way
I have read to not thin the final coat of varnish. With the weather conditions I don’t see how I can get the varnish to flow and lay right unless I use a brushing thinner of 10% or less. Any assistance would be appreciated.
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Not only do different online "experts" give different advice, but instructions virtually always assume perfect conditions which of course don't often happen. You're absolutely right, the varnish MUST be adjusted for weather conditions and use (first coat, middle coats, last coat, etc.)
Ken
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05-02-2019, 12:17 PM
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#4
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Guru
City: Narragansett Bay
Vessel Model: Grand Banks 36 Classic #715
Join Date: Sep 2016
Posts: 1,857
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The “final coat” probably should turn into 2 if you are thinning. 23 rain days in R.I. in April. Ugh!
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05-02-2019, 02:32 PM
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#5
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Guru
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,743
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I have Rebecca Whitman’s book on varnishing and will look up your situation.
But from my memory thinning varnish is a no-no. I’ve done it in many ways w no problem but the last coat should be max thick. Probably be good to have max UV protection on the last coat too.
Personally I think the best thing to do re varnish is to apply several to many coats on bare and dry wood w progressively less thinner (turp) and I usually just use Linseed oil. I know Tung oil is better but I’m not convinced it’s much better. And for best penetration I use kerosene for thinner on the first few coats.
__________________
Eric
North Western Washington State USA
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05-02-2019, 03:47 PM
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#6
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Guru
City: Quebec
Vessel Name: Bleuvet
Vessel Model: Custom Built
Join Date: Jan 2016
Posts: 4,375
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The only difference in applying a thinned varnish layer in place of a straight varnish layer is that you will apply less varnish and more thinner. As a consequence you need to apply more layers of thinned varnish to get the same level of protection/resistance.
L
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05-02-2019, 04:11 PM
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#7
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Guru
City: Brookline, NH
Vessel Name: Shalloway
Vessel Model: Defever 44, twin Perkins
Join Date: Sep 2013
Posts: 2,260
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Quote:
Originally Posted by Lou_tribal
The only difference in applying a thinned varnish layer in place of a straight varnish layer is that you will apply less varnish and more thinner. As a consequence you need to apply more layers of thinned varnish to get the same level of protection/resistance.
L
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Agreed. The issue with never thinning the last coat is one HAS to take the thickness of the varnish into consideration. Last coat or not, if the varnish has too thick a consistency it will not flow out correctly - and there are definitely circumstances that can cause the varnish to be too thick for proper wet film thickness and and/or flowout.
Ken
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05-02-2019, 04:28 PM
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#8
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TF Site Team
City: Jacksonville
Join Date: Nov 2008
Posts: 11,682
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Quote:
Originally Posted by Lou_tribal
The only difference in applying a thinned varnish layer in place of a straight varnish layer is that you will apply less varnish and more thinner. As a consequence you need to apply more layers of thinned varnish to get the same level of protection/resistance.
L
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05-02-2019, 04:55 PM
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#9
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Guru
City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,743
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I looked in the Whitman book and want to share to or so things.
The last coat isn't to be different in any way from the preceding four.
However some consideration should be given to all the solvent that is still in the previous coats having to evaporate through all the coats including the last. So longer wait times should be considered for later coats.
Attention should be given to the dew point. Some summer days are dry enough much earlier than other days. Paint as early as possible on hot days to apply cooler varnish on a cooler boat.
I could not find her saying never to thin. She talks about thinning 5 to 15% on primary coats and to use a "brushing liquid" in later stages.
__________________
Eric
North Western Washington State USA
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05-02-2019, 05:17 PM
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#10
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TF Site Team
City: Jacksonville
Join Date: Nov 2008
Posts: 11,682
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Eric: Thanks for posting that. I’ve always thinned, even the last coat, usually between 5-10%. I’ve never given any thought about the thinning solvent but it makes sense. I’ve screwed up a few jobs by rushing the final sanding by not being hard enough. Patience.
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05-02-2019, 06:32 PM
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#11
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Guru
City: Groton, CT
Vessel Name: Datenight
Vessel Model: North Pacific 45
Join Date: Jan 2008
Posts: 1,106
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Ken and Lou hit the nail on the head. Varnish does need to be adajusted to meet conditions. If it means one or two more coats so be it. You will be rewarded with a beautiful finish.
Rob
__________________
North Pacific 45
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05-12-2019, 04:46 PM
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#12
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Guru
City: Marion, Massachusetts
Vessel Name: Wanderer
Vessel Model: Pilgrim 40
Join Date: Sep 2016
Posts: 632
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I always add Penetrol, just flows better with it.
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