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Varnish adhesion issue
Marc, I have passed this one on to Epifanes as it has me stumped, you appear to have done everything correctly but have still seen a distinct separation from the wood which is something I have never seen happen before.
I will come back to you on here once I hear back from them.
Perhaps the varnish was old? Is there an expiry date on Epifanes tins (that is understandable by users)? Or it was frozen? Just throwing out ideas here.
New varnish and not frozen to my knowledge. I’m leaning towards believing it was excessive humidity during the first application stages, mostly because I have no other ideas. I remade my tests but applied two coats of Pettit wood sealer. The adhesion seems much better(knock on wood). I ironically had not wanted to use the sealer because I was afraid of crossing brands of product and having adhesion issues.
I am now scuffing up coat #6
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I’m thinking that my adhesion issue was largely due to humidity and the newness of the application. Being new to varnish I wasn’t sure how durable it should be, but the samples seem to have a greater adhesion now that it has cured longer.
I probably could have left it instead of removing and reapplying with the addition of a sealer. but, I really didn’t want to put 16 layers on a bad foundation. 🤨
Apologies that it took me a while to follow up on this here. When putting this question to the team at Epifanes this was their response:
“Concerns could possibly be…
Always stir the varnish with a paint stick into full solution before using. It is a myth that you should not stir varnish.
Did he let each coat dry fully (meaning sandable, typically 24 hours at 68F)? Epi recommends this to make sure each underlying layer is fully dry. Coating over them too soon can trap solvents, and they remain soft, while the top coat appears fully dry.
Did he use our brushing thinner? We have seen issues with the new low voc, low odor mineral spirits, and we try to advise against the use of them.
We recommend traditional oil based stains, and waiting for them to dry at least 3 days, and the more the better. We do not recommend the hybrid stains they now have. Water based stains need to dry for at least a week with low humidity.
I understand the student was trying to figure out how far the problem possibly went, but in general, the finish ideally needs to be treated gently for the first 30 days. Attempting to remove it prior to that might be easier than one might think.
We may never know why this occurred. But, these are questions I would ask with the info provided.
Feel free to have the student call our office and speak with Jason our tech sales manager if they want. He may be able to provide more insight as well.”
I thought it was particularly interesting that they expected the finish to be gently treated for the first 30 days. It would be interesting to know if you had the same issue if you had left the samples for a bit longer to harden up.
I had a similar problem 5 years ago. using interlux compass clear. The rep came out to boat to take a look. i walked him through all of my steps. He felt that i did not clean the bleaching agent off well enough. So i stripped it all off and started over. Second time around it stayed on. And now 5 years later it still looks good
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Thanks for the response from Epifanes.
I waited 24 hours between coats of varnish and several days after staining.
My control sample of no bleach and no stain also peeled easily.
I'm left believing that it was the newness of the varnish application, because I cannot get the samples to peel at this point. I did not have any varnish experience so I wasn’t sure if it was an issue or typical behavior for new varnish. It was shocking to see it pull so easily, but now I know what to expect.
thanks Dan
I would like to suggest that the keying failure could possibly be a prep issue in the sanding.
Perhaps the final sand has used a grit that is too fine to allow a key, or the operator has allowed the abrasive to wear such that it is burnishing the surface as opposed to cutting it.
The examples shown do not suggest any product failure for mine.
My own experiences suggest that some timbers will require a different grade in order to achieve a durable key to the ones suggested by the system manufacturers.