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Discussion Starter · #1 ·
Two years ago I made this hive from cedar 2x6s and gave it a few generous coats of boiled linseed oil. It looked so bad this year that I sanded it down and put 3 coats of spar varnish on it. Boat people insist on 7 or 8 coats but I doubt I'll have this out in the salt water any time soon. I'll let you all know how it works out in another 2 years.

cedarhive040319.jpg
 

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You'll be doing spar varnish again too, even though it is an outdoor finish. Boiled linseed oil is a penetrating finish. That means it soaks into the wood and then polymerizes as it cures. Its wood penetrating ability makes BLO an acceptable outdoor finish except that it is a finish that has to be reapplied every couple of years. BLO has a long cure time and it requires many coats to build up a protective surface. BLO is not UV resistant. Spar varnish is a urethane film finish. It lays on top of the the wood and has limited penetration. Urethane is not UV resistant, but spar varnish has additives to make it somewhat UV resistant, but not UV proof, and in a few years it does begin to delaminate. Clear finishes enhance the beauty of wood and they give beehives a very natural home garden kind of presentation. However clear finishes are going to let some sunlight through to the surface of the wood and it is the reflected sunlight that we see as the beautiful wood, and that same sunlight is the enemy. It breaks down the surface of the wood. And as it breaks down, the finish delaminates and comes off.

I used BLO on one of my hive stands in 2015 and put on mulitple coats. It needs to be recoated. I'm not going to do anything except put on my gloves, pour some BLO into a rag, and wipe a new layer on the hive stand. (Make sure you take care of those rags when using BLO, they are a spontaneous fire hazard).

I put spar varnish on my Warre hive. You can see the difference from two year old boxes (top 3) and brand new box (bottom) in the first picture, taken fall of 2018. The second picture is the same top 3 boxes and roof in the spring of 2017. The spar varnish film is still intact, but the fading on the stain under it obvious, so UV is still affecting the wood. When the wood surface starts to be degraded by the UV the spar varnish will start peeling off.
 

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Discussion Starter · #3 ·
Yea, I've built quite a few boats and 'bright work' definitely needs refreshing. Hopefully I will get on to it in time and then it will be a quick job with the orbital sander and a few laps around the box with more spar varnish. I couldn't find any 'before' pictures of the hive but there was quite a bit of black mold looking stuff.
 
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