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I posted a question a few months ago and we are just now getting into our home to clean up and finish the log walls on the interior. I reseached the chemical products for "bleaching" and cleaning the walls before sealing.Based on some replys I got and research We decided to go with just sanding to avoid possible damage to wood if not rinsed well enough. We today put the first coat of water based poly on and were very disappointed that the walls looked very blotchy. Not from the poly,but the sanding job we did. We used 60 grit discs to get the most yellow/dirt off. It looked like we had done a good job, but like I said, it was horrible. Before we go on to do the other rooms, does anyone have a cleaning agent the have used that is safe for the wood, but would lighten the wood and stains before we start sanding? We can't hose the upstairs walls to rinse since the second floor flooring is on, but I supose we could do the great room and downstairs that way if it was the best option. We have sanded the walls thoroughly again and will apply another coat of poly with hopefully a better result for the rooms we have already done. Any info would be great! We are going for a more natural/light look to the logs so did not apply a stain which may have helped hide some blotches! Help please! Thank you!


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Jennifer - did you guys sand everything, or only the darker yellow and/or gray spots of the wood? It's always a good idea to sand everything in a particular area to a natural breakpoint to avoid major differences. You can try a couple different things now:
1) apply a sanding sealer before you apply anything else. This will help even out porosity of the wood so you can get a more even appearance.
2) apply some of the poly over the sanding sealer and see if that did the trick. If not...
3) apply a coat of a very light stain to help hide the uneveness, then follow with a clear coat. There are stains out there that are so light, they add hardly any color but do a great job of hiding uneveness.

Hope that helps some. Post some pics if you get a minute, too. That might help, too.

Have a great day! -- Charis w/ Sashco - -
Thank you again for your information. We were sanding the entire wall, just not deep enough I guess. We sanded off the first coat of water based poly and went deeper. Someone reccomended using finer grit before applying any more poly. We have been doing a first sanding with 60 grit, then 120, then a final with 220. Needless to say, that's a lot of sanding before even one coat goes on. Not to mention the next two coats with sanding in between. The finer sanding was recommended to seal the pores of the wood. It seems to be working, but would the sanding sealer cut out a level of sanding? Would it show "blotchiness" like the poly does, or does it absorb without raising grain or highlighting? Do you know if it could be sprayed through an HVLP sprayer? I have considered a light stain, but was told that with the one coat of poly on, it would not take stain. Is that true?
I am ok with the results we are getting now, however, without "bleaching" the logs I am concerned about some of the stains we have yet to get to. Some of the mildew stains did not come out completely with sanding no matter how long we sanded. I can accept them in the one spot we did, but the others are even worse and on the great room ceiling beams. Any ideas there? Thanks so much for your time. What a learning experience this is. I just want my house to look beautiful and not "dirty" when it's done!
I will try to get some pics posted tomorrow.
Take care.
Jennifer - As Charis said, you'll need to sand the entire logs, not just the darkened/yellowed areas. As you sand, you change the porosity of the area you've sanded, which is possibly why it turned out blotchy. Even a clear finish will actually highlight the inconsistencies in the log surface. They will highlight the beauty of the wood, or any dirt or discoloration that may be there. Since you've started sanding, I would continue with that, just being sure to sand the entire surface, and then being sure to clean off any sanding dust before applying your finish. Perma Chink sells a product called Log Wash that would not require the use of a hose or power washer to rinse. A good wipe down with rags using clear water is sufficient when used for cleaning off sanding debris. On the wall you've already done, you may need to sand off what you've done and start over. Just remember, sand the entire wall, not just some areas; otherwise your blotchiness will remain. And, to agree with Charis, photos would be helpful.
Thank you for your reply. I replied to Charis' answer. If you wouldn't mind reading it and giving me your thoughts too I would really appreciate it!
Jennifer, So many thoughts... Since I don't know whose product you are using, it is very difficult for me to give advice on specifics as to do this, do that, etc. Sanding with the 220 does not actually close the pores of the wood, the heat that is generated creates a mill glaze on the surface. Depending on your Poly, this mill glaze could interfer with adhesion.

Most of the sanding sealers I'm aware of are an oil/water hybrid, and have a tendency to yellow and could cause some adhesion issues with your water based poly. Notice, I said could, not will. I would get samples and do some testing before going this route. With our products (I'm in Technical Support for Perma Chink Systems) we recommend nothing finer than 80 grit sandpaper, vacuuming off the dust, then washing with Log Wash. There are sanding disks available from Log Home supply outlets that work with an angle grinder and are quicker and last longer than sandpaper so actually become more cost effective.

Now... the mildew stains - are you sure that is what they are? Do this test.. Take a q-tip, dip it in bleach, and touch it to one of those spots. If it goes away, it is mildew, if not, then you are not dealing with mildew stains, you probably have some tannin stains. Those need to be approached in an entirely different way. Now, that is just a test, not a solution. We do not recommend cleaning your logs with bleach to remove those stains. It takes so much rinsing to get all the bleach off the logs, and you're working on the interior where that is not an option.

As to your question about putting a stain over the poly... that depends on the stain and the poly. You can not put an oil based stain over a water based product. Oils need to penetrate into the wood, and water based products prevent penetration. If you have used a film forming water based poly, you would need to use a film forming water based stain. If you think you want to go that route, get samples and do some testing before purchasing a lot of product that will not work. I would contact your Poly manufacturer and ask them if they have a stain that you could apply over it. It is always best to stay with the same manufacturer if possible in order to avoid any compatability issues.

I may be able to give better advice after seeing photos. Unfortunately when you're dealing with log & wood homes, there are no cut and dried answers.

Hope you're having a good day today..
Merry Anne
Thank you so much for your time and advice! We are using Sikkens interior clear BL for the walls. I did not know about Perma Chink at the time and since have heard great things, but probably not advisable to switch products now. I will do the test on the stains as I would like some advice there. My other question for you there a way to tell if you are having adhesion problems with the mill glaze we may be creating? There is nothing obvious at this point. We were going to try to use an 80 grit and then a 150 to cut back on a third sanding and see if that is sufficiant. I'll get some pics today and show you what we are satisfied with and what is the original "blotchiness". I will also get a pic of the stains.
Again, thank you so much! It seems like we should have left this finishing to the pros. We are planning on handing over the great room to our builder (who has done a few log homes=-but not specializing in-I think he will continue in the fashion we are-he is not a fan of chemicals on the walls and was the one to talk me out of it when we started this project) I am greatful for all of the advice.
Jennifer - What Merry Anne says above is right - sanding more doesn't close the pores. With a mill glaze, you will notice a slight shininess to some areas and, often times, the product you're using won't wet the surface properly. It may bead up (like oil/water mixing) or look "lacey" where there is mill glaze.

I would not switch products at this point in time. The Sikkens is doing what it's supposed to do. I would go with a 120 at the most, rather than a 150, then cutting out that third sanding. Test test test! That's the best thing you can do. Call Sikkens and see what they might recommend. I imagine they've come across this and will know how their products react in your specific circumstances.

Hope that helps some! Happy sanding! -- Charis w/ Sashco
By all means, continue with what you started with. There is no reason to change now. Here is a good adhesion test: Clean an area with water to make sure there is no dust residue on the surface. After it is dry, take about a 6" strip of masking tape and push it onto the wall. After about 15 minutes check it. If it is has curled up or looks like it wants to lift off, you could have adhesion issues.

I look forward to seeing photos!

Merry Anne
Ok here are stain photos. I did not check the bleach test on the peak beam (too high and no scaffold right now) but checked other areas, some came off and others did not-prob. not too helpful. There are 2 pics of the same area
The lighter beam with "spots" has been thoroughly sanded and the spots do not come off.The bleach test did not remove spots (but has one poly coat on, so don't know that it would work anyway) It was really bad to start with. We were going to accept it, but if there is something I can do, I would be happy to. FYI-there is one coat of poly on it already
The stairs--we sanded, polyed, then I saw lots of yellow like you see here. I resanded all of them thoroughly where you couldn't see the yellow-there was a little-but not much at all. Now they seem to look worse the more days that go by! It is too late for these as I already have 2 coats of poly on them, but to avoid future things like this-do you have any advice. Can it possibly be getting worse before our eyes?Stairs pic will be in another reply
I am going to address one picture at a time - Picture #053 - Here you have a combination of mold, tannin stains, and strap marks from shipping. The mold is the areas where the spots are uniform, and darker than the tannin stains beneath them. The dark stains that follow the grain of the wood are the tannin stains, and the strap marks are visible where they wrapped around the beams. If I understand you correctly, you have already put a coat of poly on them. If this is so, there is nothing you can do to remove them without sanding off the poly and starting over. I can tell from the darkness of the tannin stains you could have probably lightened them, but I've got a feeling they go too deep for an oxolic acid solution to really get them out. It may have lightened them, and made them easier to hide, but would not have completely removed them. At this point, I would be contacting Sikkens and asking for samples of one of their finishes that has good hiding power. Then, you could just coat your beams with the stain to try and get them to blend in. It would give you a little contrast in your ceiling to have the beams a darker color.
I did not put any poly on these as these are the beams in the great room, nothing has been done with them yet. I think I will look into staining the beams a different color. They are not coated with anything yet and are the areas I am the most concerned about looking dirty for the rest of time once they are sealed.
Do you think if I just did the beams in the great room and connecting loft in a different color that it would look ok? or should I do as many beams in the house that color as possible? In the kids room some of the beams are already done once in poly. Since it's only one coat though, it may be worth sanding off and starting over.
I really appreciate your help!
What would you use to lighten the tanin stains? I do have those in other areas and am not too bothered by them, but if I get particularly dark ones, I may want to lighten them. They follow the grain at least and don't look dirty to me.
An Oxolic acid solution is what you would use. It doesn't actually "remove" the stain, it just brightens it to the point where you don't see the discolorations as badly. If they don't go too deep, it will actually make them invisible. The Log Wash would remove the mold and mildew from the bare wood surface.


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