Varnish problem/Sunday evening rant.
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Larry in Champaign
- Posts: 71
- Joined: Fri Jun 18, 2004 11:03 am
- Location: Champaign, IL
- Contact:
I used Benjamin Moore Impervo 440 spar varnish on US Composites. It is a terific value! Check out this post: http://www.bearmountainboats.com/phpbb2 ... mpervo+440
As you can see, I had a similar problem with drying. I think Glenn hit the nail on the head; turn your heat up to 75-80F and see what happens.
As you can see, I had a similar problem with drying. I think Glenn hit the nail on the head; turn your heat up to 75-80F and see what happens.
I had slow drying with Interlux Schooner varnish.... 3-4 days and still tacky. That happened in a cool basement with temps about 10C, 50F. The varnish eventually did dry, although warmer temps could have helped.
Here in Canada IIRC Benjamin Moore's 440 is labelled Sunbar because of the UV blockers added... Sunbar is good quality traditional urethane varnish if the full price of a marine varnish isn't wanted.
Here in Canada IIRC Benjamin Moore's 440 is labelled Sunbar because of the UV blockers added... Sunbar is good quality traditional urethane varnish if the full price of a marine varnish isn't wanted.
epifanes still sticky
my experience with epifanes over epoxy (curing in house):
it took weeks to cure satisfactory (three coats and waiting way to long in between)
and after that, it was vulnerable for long
but in the end, the result is nice and solid
it kept me away from classic epifanes varnish for years
now, i use it for some parts and when i have time and dedication (thinned, on bare wood)
and more times i use their rapidclear (makes for faster work and durable results)
i am still not decided on my favorite varnish routine and manufacturer
eh, this might not relate to your application and trouble now
but when it does:
may be, you should leave the deck undersides as is, and be patient
and yes, experiment (as you do)
Ben (another Ben, another continent, also building a canoe ...soon ...)
lurking, enjoying all your stories, pictures and advise
it took weeks to cure satisfactory (three coats and waiting way to long in between)
and after that, it was vulnerable for long
but in the end, the result is nice and solid
it kept me away from classic epifanes varnish for years
now, i use it for some parts and when i have time and dedication (thinned, on bare wood)
and more times i use their rapidclear (makes for faster work and durable results)
i am still not decided on my favorite varnish routine and manufacturer
eh, this might not relate to your application and trouble now
but when it does:
may be, you should leave the deck undersides as is, and be patient
and yes, experiment (as you do)
Ben (another Ben, another continent, also building a canoe ...soon ...)
lurking, enjoying all your stories, pictures and advise
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Glen Smith
- Posts: 3719
- Joined: Sat May 08, 2004 9:08 am
- Location: Baie-St-Paul, Quebec, Canada
Thi is my theory on applying varnish, especially Epifanes:
Thin according to instructions when applying to bare wood. The thinner helps the varnish to penetrate deeper into the wood for optimal protection.
When applying to a glassed surface, only use enough thinner to make the brush strokes have the right "feel". Too much thinner and the brush just slips across the surface. Too little thinner and the brush is hard to drag across the surface. The right amount of thinner will make the brush move in a way that you can feel just a little drag and it will deposit the correct amount of varnish.
When you use too much thinner on a glassed surface, the thinner has nowhere to go but evaporate. However, the varnish skins over trapping the thinner inside and this prevents the varnish from hardening. When you use just a bit of thinner ( about 10% ), it evaporates before the varnish forms a skin.
The 10% figure is what I use but it should be adjusted according to the shop temperature and humidity. I always heat up my shop to about 70 or 75 degrees at aim for about 35% humidity when applying Epifanes High Gloss Spar Varnish. I also use a foam brush and applying according to Ted's recommended brushing technique.
Thin according to instructions when applying to bare wood. The thinner helps the varnish to penetrate deeper into the wood for optimal protection.
When applying to a glassed surface, only use enough thinner to make the brush strokes have the right "feel". Too much thinner and the brush just slips across the surface. Too little thinner and the brush is hard to drag across the surface. The right amount of thinner will make the brush move in a way that you can feel just a little drag and it will deposit the correct amount of varnish.
When you use too much thinner on a glassed surface, the thinner has nowhere to go but evaporate. However, the varnish skins over trapping the thinner inside and this prevents the varnish from hardening. When you use just a bit of thinner ( about 10% ), it evaporates before the varnish forms a skin.
The 10% figure is what I use but it should be adjusted according to the shop temperature and humidity. I always heat up my shop to about 70 or 75 degrees at aim for about 35% humidity when applying Epifanes High Gloss Spar Varnish. I also use a foam brush and applying according to Ted's recommended brushing technique.
ARGHHHHHH!!!! :frightened After carefully following the procedure that I successfully used under my decks, I put the first coat on the inside of the hull last night. Tonight......tacky again! I am not sure what to do. If I have to strip this coat off, I think that I am going to have to find a new varnish.
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Glen Smith
- Posts: 3719
- Joined: Sat May 08, 2004 9:08 am
- Location: Baie-St-Paul, Quebec, Canada
A test that might be useful.... apply the varnish to a previously varnished surface (eg. an old paddle) after cleaning and sanding and see if it remains tacky the same way in the same drying location.
If it cures AOK, then the difference in the epoxy on the canoe is probably causing the problems... just a thought.
If it cures AOK, then the difference in the epoxy on the canoe is probably causing the problems... just a thought.
I followed the same process that I used under my decks. Lacquer thinner, soap and water, water rinse, and wiped down with varnish thinner. At the same time that I varnished the hull, I put the 3rd coat on my gunwales and decks, and those parts dried just fine. It must be something between the epoxy and the varnish. I did not notice any blushing on the surface, but when I was cleaning the gunwale sanding dust up with a dry rag, the dust was kind of stuck to the epoxy and sticky. It was kind of weird.
The varnish seemed less tacky tonight, but I have been down this road before...
The varnish seemed less tacky tonight, but I have been down this road before...
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Glen Smith
- Posts: 3719
- Joined: Sat May 08, 2004 9:08 am
- Location: Baie-St-Paul, Quebec, Canada
Amine blush is something that can ruin your day even with some "blush-free" epoxies. It is a by-product of the hardener and usually related to fast curing hardeners. If you apply epoxy to a surface and it feels perfectly dry after a few hours, amine blush may still appear on the surface several hours later. It gives the surface an oily or waxy feeling.
Acetone and thinners do not remove blush but just spread it around. Dry sanding does not remove blush either. Blush can only be removed using water (preferably warm) and a clean cloth. Many people will add a few drops of either vinegar, ammonia or dish soap to the water but these are truly optional. Scrubbing with the rag and rinsing it often will remove the blush. You should then rinse the surface with clean water and a different rag. Once the surface has been cleaned, you should wipe it dry with paper towels, changing frequently. Note: wet-sanding will also remove blush.
Cleaning a non-blushed epoxy surface prior to applying varnish should be done with warm water or a tack cloth. Using a chemical product risks either softening the epoxy surface or leaving contaminants on the epoxy that can prevent varnish from drying.
I am also aware of at least one case where the builder had cleaned the epoxy surface with lacqueur thinner then applied varnish. He used a high quality lacqueur thinner but there was still one problem. The air was too dry in the shop and wiping the epoxy surface with rags built up an electro-static charge which actually prevented the varnish from drying. I suggested he lay a bare copper wire over the hull and attach one end to a cold water pipe. After a few hours, the varnish was dry!
Just a few things to ponder.
Edited: In the original Canoecraft, Ted mentions a final cleaning with thinner. This does not appear in the revision edition.
In one of Ted's books, he relates how the old-timers used to drape grounded chains over the hulls to discharge static-electricity.
Acetone and thinners do not remove blush but just spread it around. Dry sanding does not remove blush either. Blush can only be removed using water (preferably warm) and a clean cloth. Many people will add a few drops of either vinegar, ammonia or dish soap to the water but these are truly optional. Scrubbing with the rag and rinsing it often will remove the blush. You should then rinse the surface with clean water and a different rag. Once the surface has been cleaned, you should wipe it dry with paper towels, changing frequently. Note: wet-sanding will also remove blush.
Cleaning a non-blushed epoxy surface prior to applying varnish should be done with warm water or a tack cloth. Using a chemical product risks either softening the epoxy surface or leaving contaminants on the epoxy that can prevent varnish from drying.
I am also aware of at least one case where the builder had cleaned the epoxy surface with lacqueur thinner then applied varnish. He used a high quality lacqueur thinner but there was still one problem. The air was too dry in the shop and wiping the epoxy surface with rags built up an electro-static charge which actually prevented the varnish from drying. I suggested he lay a bare copper wire over the hull and attach one end to a cold water pipe. After a few hours, the varnish was dry!
Just a few things to ponder.
Edited: In the original Canoecraft, Ted mentions a final cleaning with thinner. This does not appear in the revision edition.
In one of Ted's books, he relates how the old-timers used to drape grounded chains over the hulls to discharge static-electricity.
Last night the inside was pretty well cured, so I flipped it and worked on the outside. I wet sanded with 220 grit, wiped down 3 times, washed with soap and water, rinsed, and wiped down with thinner. I varnished, and tonight everything on the outside seemed to be OK. I dry sanded with 400 grit, and there a couple spots that were tacky, smaller than a dime. I wiped the hull down with a rag, tack cloth, and thinner, then put a second coat of varnish on. I ended up with a few fisheyes under the varnish. I am assuming that they were low spots and may not have had the blush removed from the wet sanding? In any case, I am going to chalk this up to amine blush, and the boat is going in the water on Saturday.
Its not blush. Its not compatibility.
I had the exact same problem on my ranger. you have in sufficient airflow and the evaporating vapors from the thinner cannot leave the canoe and are setting on top of the varnish and not allowing it to set.
take a fan and blow it over the canoe to create some air turbulance. the varnish will set just fine.
I feel your pain. this added an extra month to my build a few years ago. No one here could help and i went through 3 batches of epiphanse.
It is particularly a problem with tumble home designs.
See my thread from a few years ago http://www.bearmountainboats.com/phpbb2 ... c&start=15
I had the exact same problem on my ranger. you have in sufficient airflow and the evaporating vapors from the thinner cannot leave the canoe and are setting on top of the varnish and not allowing it to set.
take a fan and blow it over the canoe to create some air turbulance. the varnish will set just fine.
I feel your pain. this added an extra month to my build a few years ago. No one here could help and i went through 3 batches of epiphanse.
It is particularly a problem with tumble home designs.
See my thread from a few years ago http://www.bearmountainboats.com/phpbb2 ... c&start=15