Reply To: Sapwood for external door
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You said you are a beginner, so I’d like to try to simplify and clarify things for you. First, it is good that you are thinking about the reality of the wood and learning about it, e.g., sapwood vs. heartwood, but my suggestion is to just build the door as long as the wood seems strong right now. If you need to rebuild the door in the future, so be it. You’ll have more experience then, but right now you are in danger of getting bogged down in details and not getting started. So, just go ahead and see how things go.
With regard to finishing, I do something like what @lorenzojose describes for interior furniture, but with far fewer steps / layers. I apply General Finishes dye stain for color, then wipe a coat of their Arm-R-Seal, which is oil based, and then apply their water based topcoat (High Performance). The reason for the oil based Arm-R-Seal is that, since I am not always spraying, it locks down the water based dye and keeps it from being picked up by the water based topcoat. Really, though, I could just keep going with the Arm-R-Seal, but it runs easily and requires more time to dry between coats. Also, it is for indoor use.
If you are doing something fairly simple, like a door, I think you could skip the razamataz of so many different coats and just go from water based dye stain or General Finishes stain to a water based topcoat. Just don’t work the first coat of topcoat. “Put it and leave it.” I don’t know how good the General Finishes Enduro 450 is (a water based exterior topcoat), but if you find it acceptable, then a simplified finishing schedule is to just apply the general finishes dye stain or stain, let it dry overnight, and then move on to the Enduro 450. No oxalic acid, no shellac, no sanding sealer. You’d only need the oxalic acid if you want to end up with a light color. If you are happy darkening everything to be something like the darker heartwood, or a bit darker, you can skip it. I understand why Larry wants to use it, but for a beginner on a first project, it’s an extra step and a non-trivial one.
So, those are the simplifications. Here are some clarifications:
1. It is okay to put oil over water, but things must be dry, dry, dry. Give the water based coat at least 24 hours to dry. I routinely put oil over water with General Finishes and know they are compatible. If you use other brands or mix brands, you’ll need to test.
2. It is also okay to put water over oil, but the oil must dry at least 72 hours before applying the water based coat on top. I’ve had cases where I needed to wait much, much, much longer. It is important to note that “oil based” means something like Arm-R-Seal, i.e., a varnish with drying agents, and does not mean BLO or other true oil. Again, general finishes stuff is compatible between water and oil in my experience. If you sense any tackiness or strong odor, it needs to dry more. Resinous wood, like pine, can give trouble here.
3. I will disagree with Larry in one detail. Do not try to remove the fuzz after you put on the water based dye. Unless you are super skilled, you will almost certainly sand through your color. Ignore the fuzz after putting on the dye stain or stain. Get your first coat of finish on over the dye or stain and then give *one* wipe with 600 grit. I like the foam backed Rhynosoft pads. It’s not sanding…just one wipe. Stay away from corners, mouldings, etc. This will remove about 1/3 of the fuzz. Ignore the rest, stifle the worries that you are ruining the project, and put on your second coat. After the second coat, again wipe with 600. You can be more aggressive now *if* you are using a water based finish because you have some finish down, although it is easy to sand through corners. If you are using oils that go on with thinner coats, continue to take great care and continue with light wipes between coats. Continue like this to build your film.
I think you will find this approach to fuzz much more feasible. You simply must have something to sand and, after dye, there’s nothing to sand. There’s not enough binder in it. What I’m describing is a mixture of just burying the fuzz in the finish, where it disappears, and progressively removing it as you build up the finish coats. With the General Finishes products, at least, you do not need the sanding sealer. The sanding will be easy enough if done as I described. You don’t need sealers. The finish is the sealer.
Hope this helps. If you want to go even simpler, pick out a General Finishes water based STAIN (rather than dye), wipe it on, wipe off the excess, let it dry. Then, start applying Enduro 450, but research whether it is okay. I know one person that uses it, but I’ve not used it myself. Larry has a lot of experience, so if his favorite spar varnish is compatible directly over the GF dye stain or the GF stain, that’s probably a great option. Larry, why the gel topcoat *and* spar varnish? Were you thinking a colored gel coat and it was for toning/glazing?
Whatever you decide, test the finishing on scrap.
We didn’t need to talk about blotching because you are using oak. That’s a good thing.
Ever considered a glass storm door?
- This reply was modified 5 years, 1 month ago by Ed.
- This reply was modified 5 years, 1 month ago by Ed.