I’m building a small side table with a circular top out of QS white oak. The circle
was rough cut on the band saw and finished at the router table. The first attached photo
show the outside edge (after a little sanding). The edge has been wiped with mineral
spirits to increase contrast. The edge is very blotchy, especially on the end grain portion.
Any idea what this is, and how to deal with it during finishing?
Incidentally, the second photo shows the same effect on the cutoffs after the initial
band sawing. I’m assuming this means the blotches are not the result of the routering
or the sanding.
Any help would be most appreciated!
Replies
First, I would make sure you sand the edge to the same grit and smoothness. Get rid of any burnishing from the router. Then try again with MS. But really, I believe you will apply a stain to the table, right? The problem will probably go away with good sanding.
The rough unsanded or minimally sanded edge grain, particularly end grain, will darken a lot with MS or any stain. You need to get it sanded, as ysu65 said, to the same smoothness as the top or even finer. When I'm going to have exposed edges like that, I always go at least one grit finer, sometimes two. The end grain of oak and other coarse grain wood will soak up a lot of liquid. You must "polish" them very smooth for the color to come out about the same as the surface grain. Use your scrap cut-offs as a test before final finishing.
Thanks ysu65 and bilyo. Using a test piece I compared sanding to 220 (including all intermediate grits) to both unsanded (straight off the band saw) and minimally sanded (80 grit). Wiping on MS showed the same blotching in all cases, with no (or very little) difference between them. I may try still finer grits, but I'm doubtful.
It's interesting that the light blotches are mostly in the center of any given cross cut; they do not seem to extend to the board's surfaces. This has me wondering about a moisture gradient in the wood. My Lingnomat scanner suggests a mc of around 7.5% at 1/4" depth but 8.5% at 3/4".
How thick is the top? Based on the scrap on the bench it's not much more than an inch so the meter readings don't make sense. Try reading the same spot on the board from both sides with nothing behind it, I'm betting on no noticable diff.
1". I tried what _MJ_ suggested, and find that regardless of which side I measure and whether the board is on my benchtop or is suspended above it, there is still a significant difference between the mc measured at 1/4" and 3/4". The scanner, of course, averages in some way over depth. It seems plausible to me that if the actual mc in the center of the board is higher than out near the surfaces, the scanner would detect this and the 3/4" mc reading would be higher than the 1/4". Whether this is the source of the blotching is another matter.
OK, try this on a scrap piece. Sand with 220 until it is vey smooth to the touch. Then rub on the stain you will use for the top and remove excess after a few minutes. Let us know how that turned out. Tom
When you sand through all the grits to 220, are you sanding with each grit until all of the scratches from the previous grit are gone. If not, do so. Continue through 320 especially on the end grain. MS is very watery and more of it is taken up by the pores. Once suitably "polished", try some gel stain or some dye diluted in alcohol. This might work better. With either one, you will need to apply a coat or two of clear finish (spray shellac or lacquer work fine) to see how it is going to look.
Truth be told, I've not yet decided on the finish I will use. Was thinking of fuming first... But regardless of the finish, I'd like to better understand what is really going on. I'll also try sanding to 320 and beyond and see what happens.
Thanks again!
Experiment on scraps first then you don't necessarily need to know your final finish. I'm no expert on fuming. I'm guessing if you do that, what is happening now with the MS won't matter much; except the sanding part is still important.
How is the lumber cut...quartered, rift, flat? Could that be hidden internal figure we're seeing?
One thing I consider in routing circles. Edge grain and end grains should be routed in different. In other words, climb cut the edge grains and do the end grains normally. I picked that up on WoodMagazine.com and it's worked well for me.
The wood is quartersawn white oak. The router does not seem to be the culprit as the blotches are present at simple band sawn or table sawn crosscuts. I've now sanded some samples to 600 grit; the blotches still show up clearly after wiping with mineral spirits.
Split the sample board on the bandsaw to see if it is figure?
The boards I've shown up to now were originally 6/4 quartersawn white oak, which I milled to 1" thickness for the table top. The wood had sat stickered in my garage shop for 4 months before I touched it. Here's an image of a table sawn cross-cut done a few days ago through an 8/4 QSWO slab bought and stored just like the 6/4 stuff. The end grain has again been wiped with mineral spirits to enhance contrast. The same interior blotch is present; it is surrounded on all 4 sides by a darker region. Sure seems to suggest moisture creeping out of (or into!) the depths of the slab.
BTW, this lumber was bought in Los Angeles and stored in my shop in Pasadena. Humidity stays below 50% virtually all the time and it almost never rains! Go figure...
Any ammonia in your environment, it looks like it’s been fumed.
I see this same thing frequently with white oak. Personally, it doesn't bother me and I live with it. It is not a sanding or milling issue. It isn't figure. I suspect it is related to the natural pore filling in white oak. White oak is different from many other trees because it fills its pores with a solid substance as it grows. This is why white oak is much more water/weather resistant than red oak and other woods. My hunch is that this substance oxidizes/changes color with time and this creates a ring around the outside of the board including the end. I have noted that if I only trim a small amount off the end of the board the color change isn't there, but if I cut into the middle of a board it appears. Fuming has not improved this color change. What I don't know is if the change is related to the kilning process or just time. You could try heat after you reach your final dimension to see if this fixes the issue or you could just wait and see if it resolves with time. I think this color change is similar to what we see with cherry, but it will not resolve under a finish (I just checked my dining room table and it is still present on the end after 5 years).
Thanks Jake_W; good to hear that others have encountered this issue. This is my first white oak project (been cherry, mostly, up to now), so it was a surprise for me to see this. I've not yet run across any mention of this effect in the many white oak project articles in FWW.
I'm trying some simple fuming experiments on samples and have seen some encouraging results. If they hold up I'll post about them.
Yep, that's just internal color variations in the oak. The only way to hide it is with dye and stain.
A combination of both is best, using dye first, then sealer, then gel stain.
Best
Fuming if it doesn't kill you will darken the wood. I would be leary of using any dyes, stains etc prior to fuming. There could be a reaction. I would think from the pictures that you have either a moisture issue or a density issue. Oak air dried takes a long time, measured in years. Oak will absorb moisture from the air. When the humidity was high ,before I knew anything about dehumidifiers I would crank up the heat in the shop working with Oak. So, 90 percent humidity and 90 degree air temperature and I would maybe heat the shop to 110 or more and sweat like a pig. I'm thinking given your location that it's the grain pattern or density. And since you live in Pasadena of course you are considering fuming. If your trying to replicate an arts and crafts finish its probably the only proper way. You will get a lighter color on the side grain than the end grain, that comes with the territory. If on a fresh cut that pattern is always present my guess it's simply a matter of those boards / that tree. I'd try fuming a scrap and see what happens.
Thanks, Pantalones868. I've been experimenting with fuming and have survived so far! We'll see.
I don't think this is just natural variations in the wood. It's clear from the
photos that the blotching stays away from the long grain sides of any given sample of the stock. It's as though something is creeping inward over time (years? I hope not...) after the original milling at the sawmill. The darker outer layer is about 1/2" wide all round. In the 8/4 photo you can see this clearly. In a thinner board, 4/4 S2S, there is no blotching in the interior; perhaps the "creeping in" has met in the middle?
Well, you could put it aside and maybe the creep will finish creeping in a few years! Sometimes the wood is just cursed. I'm in the process of doing 5 tables. The tops have a laminated design and besides some mistakes I made in the order of process that made it harder than it needed to be there was one top that no matter whether it was the first,middle or last screwed up. I would fix it and next step it would blow up and id fix it until the final step when it could no longer be fixed and so I'm making 4 tables. My conclusion was that it had a curse!
It seems that fuming does remove the blotches I have been describing. The attached figure shows the end grain of a sample before fuming, after 6 hours of fuming, and after 23 hours. After 6 hours the blotch has more or less disappeared. 23 hours just darkens things a bit more.
I am using janitorial ammonia from Ace Hardware with a small dish of the stuff inside a larger sealed glass container holding the sample.
This sample comes from the same board that I am using for the table top. The piece shown is roughly 1" x 3" x 1/2". The blotch was apparent on both sides of the sample and was removed equally by the fuming.
Wouldn't want to extrapolate beyond these few pieces I've tried, but fuming does appear to solve the problem at hand.
What's your set up for fuming? Inside ,outside. What is the amount of ammonia in the ammonia/ product name.
I looked it up. Ace Janitorial ammonia is only 10 percent ammonium hydroxide. Thats pretty low. Seems you have a result though. I've done this but at industrial strength 26 percent I think, been a long time. I have some projects and a bunch of old " french" oak wine barrel material and have been thinking of fuming . Wondering if I'm going to have difficulty getting industrial strength ammonia. Since ,particularly here in California, the politicians keep trying to keep me away from things that actually do the job. Someone took my plastic resin glue that I rely on for a whole thing I do. 5 minute epoxy from the Ace doesn't set up in 5 minutes anymore or 5 hours or 50 hours! I know a guy who makes these decisions for us and really I wouldn't let him wash my car!
Here's my ridiculously simple set up; belongs in a grade-school science fair!
But it works, at least for these small samples I'm testing now. In the pic you see two glass sealable containers. The small one holds the ammonia and obviously remains open. The larger one is for the sample (there is a piece of 8/4 QSWO in there now). The snap-on lid is off to the side. Yes, the ammonia is 10% janitorial strength. So far, I see no need to go to the stronger stuff. The whole thing is on the back porch outside.
You can get the more concentrated stuff on amazon:
https://www.amazon.com/Ammonium-Hydroxide-Reagent-Grade-Purity/dp/B00URU19UI/ref=sr_1_2?crid=IMBXCYWXHEYE&keywords=ammonium+hydroxide&qid=1638650411&sprefix=ammonium+h%2Caps%2C253&sr=8-2
I know what you mean about restrictions on stuff in CA. It's not all nuts, but some sure is. It makes me laugh though to see entire aisles at Ace devoted to methylene chloride paint removers, weed killers, etc. Those things are real killers and no peep (yet) from the state.
Your photo of the 8/4 slice with all four sides showing the stain is interesting, is it possible your oak was exposed to a (mild?) chemical gas leak of some kind at your wood supplier or in your shop? Is your supplier in an industrial area? Do you store your ammonia bottle in your shop?
Thanks, Karl_Ko. Well, I can't rule this out completely; it's LA after all! But its not due to ammonia in my shop; never had any till I started these experiments.
However, I will say that all the white oak I see at my supplier and others around town has the usual blonde appearance on their exterior surfaces. Nothing out of the ordinary.
I'm attaching a photo of that 8/4 slice you mentioned, before and after fuming. Again, the blotches disappear upon fuming. This is obviously from a different board that the 6/4 pieces I showed before, and likely from a different tree altogether.
I like exposing end grain in my work and hadn't run across this in any of my wood previously so I was intrigued. This article from the Forest Products Laboratory may possibly shed some light on the staining you're seeing. The bottom of page 195 shows a photo of a white oak example with an effect similar to your sample. There's some explanation around potential cause (in their example, improper drying technique which allowed a mold type fungus to grow): https://www.fpl.fs.fed.us/documnts/usda/ah188/chapter08.pdf
Wow, that's really interesting! Thanks for the link, Karl_Ko.
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