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Thread: CPES Under Varnish

  1. #1
    Join Date
    Jul 2002
    Location
    Seattle, WA
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    Default CPES Under Varnish

    I am not a true believer in the Gospel of CPES like some of you guys...especially you Northern California evangelist boys...I think it is a terrific sealer, but am dubious about some of its other miracle properties....

    but I think I have a good use for it.

    I am doing the cap rail on a large boat...It has cracks here and there. Also joints do not appear to have been sealed well. It blew off the varnish over the winter.

    Thinking of coating the rail with CPES, paying careful attention to cracks and joints. Will then put on a few coats of Pettit 2018 clear sealer before proceeding to Epifanes.

    Questions: Does CPES darken the wood excessively? How long is best to wait before overcoating CPES? CPES tech support advises waiting one day or until it stops smelling skunky. They add it will blush if it rains.

    I have bare wood right now...trying to come up with a strategy to seal the wood between rain in Seattle...Monday and Tuesday appear to be consequecutive days...I am presuming I need at least two days to do the CPES and then to overcoat it with sealer/varnish. By the way...weather here is 55 to 60...intermittent showers...two days good weather is rare this spring. But once I get the wood sealed I can simple jump on a good day to add a coat of varnish.

    Hope I am making sense. Any comments will be cheerfully read....thanks in advance.

  2. #2
    Join Date
    Aug 2005
    Location
    SF Bay Area- Richmond
    Posts
    15,637

    Default Re: CPES Under Varnish

    Can we assume you're using Smith & Co. CPES?

    I'd just call them and go with their recommendations -- Steve Smith is a very technical guy and knows his products well. Depending on the weather and what you use (Warm/Cold Weather Formula), the cure time can range from a day to a week, but most folks go for a hot-coat system where you varnish over the non-tacky but uncured CPES.

    I've only done a bit of varnish and paint over CPES on small boats, and it has worked well -- but all was outdoors in warm weather, not on larger boats that live in the water.
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  3. #3
    Join Date
    Apr 1999
    Location
    Hyannis, MA, USA
    Posts
    46,138

    Default Re: CPES Under Varnish

    Yes, but maybe not real varnish. CPES is a great sealer that is waterproof in any normal (non-boiling) sense but is vapor permiable. Old boat toe rails are especially prone to lifting varnish because moisture in the hull travels up the fastenings through the caprail and around the bungs to the wood/varnish interface where the vapor is held by the varnish. Pressure does the rest.

    I like the Cetol natural teak formulation that does not have the orange of older cetols, and cetol is vapor permiable so it won't lift off the way real varnish will. It cannot be as high a gloss as the best varnish but which looks better; slightly duller intact finish or bubbly blisters?

  4. #4
    Join Date
    Apr 1999
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    Now, there's a long story...
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    1,573

    Default Re: CPES Under Varnish

    Mr. Ford,
    To answer your question directly, best is to apply varnish over CPES between 1 and 3 days. Shorter than 1 and it's still outgassing, after 3 you lose the molecular bond.

    I did not notice that it darkened the wood at all. But this was over a mahogany, not sure what it would do on something light, for example white cedar or spruce. Probably not any darker than Epis, if that much. It's been a while since I mixed a batch, but I don't remember it having a color at all... but my memory is not what it's once been.
    Heute ist so ein schöne Tag...

  5. #5
    Join Date
    Jul 2002
    Location
    Seattle, WA
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    Default Re: CPES Under Varnish

    Thanks gentlemen!

  6. #6
    Join Date
    Dec 2007
    Location
    California Delta
    Posts
    1,265

    Default Re: CPES Under Varnish

    I also prefer Pettit Clear Sealer under varnish. I recommend another product for sealing narrow cracks in weathered joins and around plugs: Captain Tolley's Creeping Crack Cure.

    This product has the consistency of water and penetrates like CPES. It follows cracks and voids up to a couple of feet in length. Creeping Crack Cure is a liquid polyurethane featuring much higher build than CPES. To seal these cracks I applied CCC with a dropper until the crack was filled. As the product soaked in I repeated this process several times over a couple of hours. Then I let it cure overnight and repeated the process once or twice the next day. CC provides a permanent seal that completely fills voids. I cleaned up with a final sanding followed by stain, sealer and varnish. CCC is clear but appears black under varnish.

    I used CCC on these cracks 15 years ago. The cracks have not grown as they are completely sealed and finished flat under varnish. I took this picture several years ago. The only difference today is that the varnish is deeper and has a higher gloss.

    "Whiskey is for drinking, water is for fighting over." -Samuel Clemens

  7. #7
    Join Date
    Dec 2007
    Location
    California Delta
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    Default Re: CPES Under Varnish

    You may find that narrow voids along some cracks and joins run all the way through your wood. If it does Creeping Crack Cure will just run out the underside and you won't be able to fill the void. CCC travels by both gravity and capillary action. If that happens just cover the underside of the void with electrical tape. You can then fill the void. You will be able to remove the tape after CCC cures.
    "Whiskey is for drinking, water is for fighting over." -Samuel Clemens

  8. #8
    Join Date
    Dec 2007
    Location
    California Delta
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    Default Re: CPES Under Varnish

    I did a quick check of my favorite marine stores and was surprised to discover that Jamestown Distributors and Defender don't stock Creeping Crack Cure. West Marine stocks this product in their epoxy department. It's expensive by ounce but I believe CCC is worth every penny. I also use it to toughen up wooden screw holes where fasteners are removed and refastened on a frequent basis, like deck hardware.



    Creeping Crack Cure comes from the UK. Here is the website. I don't necessarily recommend all of the marine product applications suggested on this site.

    http://www.captaintolley.com/
    "Whiskey is for drinking, water is for fighting over." -Samuel Clemens

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