Replies

1. 
   HowardAcheson | Sep 01, 2008 07:29am | #1

   The problem is most likely the glass door. It caused the finish to be heated and caused the bubbling. This would be a problem if the door faces the sun.

   Howie.........
1. 
   Gretchen | Sep 01, 2008 02:51pm | #2

   Plus maybe using a poly varnish over the shellac? Dewaxed?Gretchen

2. 
   Rich14 | Sep 01, 2008 03:56pm | #3

   "I would like to control wood movement as much as possible, so I like the idea of sealing the wood with shellac, but I also need to make it as UV and heat resistant as possible. I would appreciate any advice or suggestions. And obviously paint isn't an option."

   Well, good luck with those dreams! Unfortunately, mother nature usually wins. As much as any of us who builds a door from hardwood doesn't want to hear it, paint is the best finish for an exterior door.

   Shellac is a great substance to use to seal wood, but it's not superior to the varnish you used over it for "control" of moisture. (Neither will really control - just slow)

   Did you use shellac that contained wax? Exactly what type of spar varnish did you use?

   After you get done scraping/sanding the mess off, you will probably be down to bare wood (hard to prevent that). I recommend starting over with a true marine spar varnish - available only at marine supply outlets. No shellac. Don't use anything from Big Box stores or ordinary paint stores, no matter what the product says. You want brands such as Interlux, Epiphanes, Z Spar. It's expensive and worth it.

   Apply exactly as recommended on the can of whatever brand you buy. Usually, diluting the first coat 50% with solvent is a good step for initial adhesion to the wood itself.

   Marine Spar, as you request, is "as UV and heat resistant as possible" . . .

   . . . except for paint!

   Rich

   
   

   ---

   Edited 9/1/2008 9:02 am ET by Rich14

3. 
   sapwood | Sep 01, 2008 11:51pm | #4

   You may have less of a problem with UV than you think. Ordinary glass blocks most of the UV light. You can get museum quality glass that will block even more. So your glass screen door (is that an oxymoron or something?) will help a lot.

1. 
   brucet9 | Sep 02, 2008 08:15am | #6

   "...glass screen door (is that an oxymoron or something?"Maybe glass fiber mesh? :)
   BruceT

1. 
   Gretchen | Sep 02, 2008 04:55pm | #7

   Probably "glass storm door". Gretchen

4. 
   SteveSchoene | Sep 02, 2008 05:04am | #5

   First thing to do is to remove the glass door in front.  It acts as a green house  may reach temperatures in the sun way beyond the capacity of clear finishes to withstand.  (Put a thermometer under the storm door if you doubt.)  Besides, why hide a mahogany door behind glass.  You made the door from mahogany to lessen the wood movement problem. 

   Then you will really need spar varnish.  But it must really be spar varnish.  None of the big box stores carry real spar varnish.  Paint stores only carry real spar varnish if they are located in towns addicted to sailing, and not always then.  There are three quality marine spar varnishes.  Epifanes Clear Gloss, Interlux Schooner, and Pettit Captain's.   These finishes need thickness to help them prevent damage to the wood, so use all the recommended 6 or so coats. If you sand any coats heavily to fill pores with finish, don't count them as full coats Since it sounds like you have plenty of sun, also expect to add a refresher coat about every year.  Patch any dings quickly.  A brass kick plate might reduce refinishing. 

   I suppose you could also use Interlux Perfection which is a two-part pure polyurethane, but the stripping and rinsing and sanding necessary to use that will be an effort, and it will cost about $80 for a quart of the material and required thinner.  It might be a bit tougher, but boy when you do need to refinish, you will have to sand it off, since it will laugh at methylene chloride.  But it still won't be forever.  The sun is all powerful--the source of all enegy on the earth aside from nuclear power. 

5. 
   doorboy | Sep 02, 2008 05:09pm | #8

   Remember as kids when we used to hold a magnifying glass in the sun to try to start a fire? The storm door that faces the sun is a similar principle. While it won't start a fire, the built-up heat is trapped in those couple of inches between the two doors and it leads to damage.
   Also, a dark stain or finish on the entry door can build up heat.
   WDMA recommends AGAINST the use of a dark stain or finish on exterior doors.
1. 
   Gretchen | Sep 02, 2008 06:03pm | #9

   Why could you not have any stain you want on your doors. That seems a bit over the top. I have had a dark brown door for 30 years, and see PLENTY of others.  Doors are painted black all the time also.

   Gretchen

   Edited 9/2/2008 11:03 am ET by Gretchen

1. 
   SteveSchoene | Sep 02, 2008 08:01pm | #10

   It's just the simple reality that dark colors absorb more heat.  This creates a greater differential between interior and exterior, hence wood movement issues and the like.  It's not an issue if the door is shaded for substantial periods of the day, whether with a entry porch or by having a north or mostly north exposure. You can still see a lot of successful dark doors, but there are a lot of shaded doors that make it possible.  Also a lot of doors you see may be sources of work and expense for their owners, few of whom are going to advertise their bad fortune. 

2. 
   doorboy | Sep 02, 2008 08:07pm | #11

   I'm not naive enough to not notice darkly stained and painted doors myself. I'm only pointing out the WDMA recommendations--along with AWI and most door manufacturers'.
   The reason is: the darker the finish, the more the doors retain heat. Heat=possible failure.Peyton Manning-- "I won this game as a team."

2. 
   Rich14 | Sep 03, 2008 01:10am | #12

   doorboy,Using a magnifying glass to focus an image of the sun into a virtual point of hundreds of degrees F, well over the ignition point of wood, and a glass door trapping the heat of the sun in a closed space are, well, quite different principles of heating.But you're right that dark doors get warmer than light doors when exposed to sunlight.Rich

1. 
   doorboy | Sep 03, 2008 04:23pm | #13

   I can be persuaded to agree with you Rich. But do you not agree with me that sunlight through a GLASS door builds up heat greater than a door with NO outer door?

   Edited 9/3/2008 9:25 am by doorboy

1. 
   acornw | Sep 03, 2008 05:00pm | #14

   The addition of a glass door - "storm" door if you will - makes the door unit an efficient solar collector. Heat from UV will destroy anything in there. Reading the WDMA and other professional data closely will instruct one to set the storm door with a 3/4" gap at the top and the bottom. Then it "doesn't protect the door" they scream. There is no need for a proper wood door to have a "storm" door over it to protect it. UV is the culprit, not wet. Storm doors cause more damage than they prevent, unless north facing in a northern climate. It is all about site and exposure. In the 70's, when I was just learning about these things, I used to get these half melted gobs of plastic that were plant-on "molding" used to disguise metal doors. I was to reproduce them in wood. I assumed, incorrectly it turns out, that the alleged molding was damaged by a fire. What else could get so hot to melt the plastic like that? After about 6 or 7 of these, I commented to my mentor about the high number of fires. When he was done laughing, he explained the dark painted doors were located behind a storm door, and the solar heat built up and caused the meltdown. As for dark stains, they will shorten the life of both the finish and the door if exposed. If one uses good wood, then there should be no reason to make the wood look like something it is not. To further complicate, modern, efficient houses have eliminated things like overhangs and set backs as too costly, leaving a door out in the weather, unprotected for both the door and visitors. A search here should indicate that Sikkens is preferred by most professional door finishers over spar varnish. Spar is meant to be removed as it ages, and is part of wood boat maintenance. It is not easy to remove spar from a door without taking down the door and boarding up. Sikkens is one product that avoids that. Dave S
   http://www.acornwoodworks.com

1. 
   Gretchen | Sep 03, 2008 05:13pm | #15

   Storm doors in my part of the country are not for "storms" but for opening the front door to the outside with protection--it makes the front hall quite nice and sunny. It is more/all about decor.  And you can do it year round with a mild climate. Just an FYI.Gretchen

2. 
   Rich14 | Sep 04, 2008 12:51am | #17

   Dave,All good points.I used to live in Phila., PA. Just about every row house in Northeast Philly had storm doors. Well, they were storm doors in winter, they converted to screen doors in summer.They were a way of life there. I can't recall any melted doors or door moldings. Philly. doors are TOUGH!Rch

2. 
   Rich14 | Sep 04, 2008 12:46am | #16

   "do you not agree with me that sunlight through a GLASS door builds up heat greater than a door with NO outer door?"Of course! It's a "solar collector."Rich