What could cause this

[sailaway78]

Almost sort of goes along with the Rich303 deal. I had a whole bunch of smaller teak trim pieces out of the boat to refinish. Had them all done, and they looked pretty good. Then Mainesail and TonyB posted up some of their work. Well, this won't do. So I resanded, really really good, wiped down with acetone, and revarnished. WOW Now they really look excellent. So, I have four coats of varnish on, they look perfect, but as per what the more knowledgable than I do, was going to sand lightly, and add one more perfect coat. This last coat went on with little bitty air bubbles in it. Almost like it foamed a little when I brushed it on. Most I got rid of by lightly brushing over again. But a few remained. When the varnish dried, left little white spots. What the hell causes this. Nothing done or used that is any different. Exact same varnish out of the same can, same brush, same cleaning methods. The only thing I have changed is the brand of thinner used to clean the brush. So, you guys in the know, what did I screw up. I know I have to sand again, but certainly don't want a repeat performance.

 

[CalebD]

Was it cooler when yo did the last coat?

When it is warm (around 75 - 80) and your work is warm it should warm the varnish as it goes on helping any bubbles escape. Did you pour the varnish through a varnish cheesecloth filter before using (to get out any congealed bits)? Did you use the varnish right out of the can? Was the humidity high the day you applied the last coat? Did you apply the last coat late in the afternoon so that it cooled down rapidly and would not let the bubbles out? Does the last coat need to be thinned also? I have not used Epiphanes but use Interlux Schooner for my exterior teak. I hear that Epiphanes is pretty thick.Sorry to hear that all your hard work has to be re-coated yet again. Don't sweat it. I only ask the questions above from reading Rebecca Wittman's book on Brightwork - and she is a real varnish 'Nazi'. I hardly follow any of her rules and (mostly) get good results. I still have a love/hate relationship with varnish and am leaning in a kind of Cetol way for the next overhaul.I am curious what others have to say.

 

[Roger (Ninette Manitoba)]

varnish on dropping temperatures

Here is what is happening, (assuming you have not stirred your varnish and introduced bubbles into the can). When you brush on varnish, you should only do so when the temperature is dropping. Rising temps cause micro bubbles in the wood to expand and these get trapped in the drying varnish. Cooling temps cause these micro bubbles to contract and therefore not show up in the drying varnish. Either varnish in the decreasing temps of late afternoon, or raise the temp in the room before varnishing, then turn it down while you are varnishing.The other possibility is that when you are brushing you slide excess varnish off your brush against the inside rim of the can. This introduces bubbles to your varnish. Instead dip slightly and brush directly, not wiping your brush as you go. If you must clean your brush, do so in an empty container so as not to introduce bubbles into your can.Finally, place your can of varnish in a sink/bowl of warm water for an hour before you varnish. This warms it up and removes any bubbles, (assuming of course that you did not shake the can prior). Remove the can from the warm water when you are ready to apply the varnish. It slowly cools and bubbles contract rather than expand in the heat of the air.All of these are simple tricks that make for a nicer varnish finish.

 

[Rich (P303)]

There...

you had to make things perfect... didn't you! At least the thinner didn't spill over... and start the house on fire.You will get it right... a couple of good posts here.

 

[Fred Ficarra7897]

I'm still glad that

I changed to plastic and stainless!

 

[newly anonymous]

the real mistake...

...was in deciding that the 5th coat was going to be your last. You jinxed those bubbles into the varnish. I never know how many coats I'm going to do when I set out. I just keep applying coats and sanding out the bubbles until, magically, one of the coats looks too good to sand. That's when you know you're done.For what it's worth, I also found it easier to "brush" out any bubbles that happen during the application process when I switched from natural bristles to a foam brush.