Raised Panel End Grain Sanding


Hoping someone can help...
I operate a small door company and we're having a problem with raised panel end grains.
We have a very expensive shape and sand machine....all set up correctly etc...
No matter what setups I use when the panels are stained....the end grains come out very dark and splotchy.
I know the big companies sand end grain effectively. What are some tips everyone has? I've read some of the other posts but people speak in generalities.
I need specific tips....any help appreciated.
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Were you able to do this before the machine? What is the final grit used by this machine? Tried a finer grit? Have you tried hand sanding afterwards with finer grits? Fine grit in a flap sander may work depending on profile. A lot depends on your wood, finishing method, expectations, experience... Is it just the stain that shows this off, is the stain just soaking into the poorly sanded areas? Or all end grain areas? Have you tried a sealer/sizing for the end grain before finishing? Or other finishing technique (pigment in the finish)?

-------------------- Steve Jensen Abbotsford B.C. snipped-for-privacy@canada.mortise.com chopping out the mortise. BBS'ing since 1982 at 300 bps. Surfing along at 19200 bps since 95. WW'ing since 1985 LV Cust #4114
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properly. Consider large Crown Moulding or other large and complex wood items - it would be impractical to sand these. Similarly, it would not be practical to sand raised panels effectively in the production environment without destroying the fine features (crisp lines, etc) When the major manufacturers cut wood they are using large machines...this allows for very high speed (critical) and also increased pressure of the wood item against the cutter. The slower the cutter, the slower the feed rate. The last point is the condition of the cutter....it needs to be razor sharp. A few months back a local contractor came to me with a similar problem. In the end, I find he is cutting raised panels on a table saw. While that is fine for *home shop* efforts, it is not going to provide the clean finish of a smooth/closed patina. I make panels on a Shaper (Grizzly) and only experience *open* end grain when the cutter is dying. There is so much more to be said for each point I have mentioned above. To summarize, the variables are:
Cutter condition Cutter speed Pressure against cutter Feed rate
What woods are you cutting and what is the machinery you are using?
One solution is to seal the entire door before stain.
J
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Seal the endgrain so it won't absorb so much. Two ways come to mind that are commonly used. First is to sand with super fine paper to heat the wood, closing the pores and hardening the end grain - burnishing. Second is to use a wash coat of sanding sealer like a 1# cut of shellac.
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George wrote:

Your problem is more likely to be the finishing than the sanding.

Bingo.
End grain always absorbs more stain or finish than long grain.
It is quite likely that the other companies are not staining thier panels. They may be toning them instead, which is the application of a colored film finish, typically on top of a clear sealer coat.
You should be able to get good results using 1 lb blond shellac to seal the panel and then go over that with a darker shellac or laquer or polyurethane with dye added. Then your protective top coat.
Some woods (even within the same species) tend to be blothier than others.
--

FF


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I hand sand with the grain with a higher/finer grit sand paper wrapped around a wood block.
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I can't give you specifics on the machine, but I have found that sanding to at least one to two grits higher than for the non-end grain parts makes the finish come out much closer to the rest of the piece.
+--------------------------------------------------------------------------------+ If you're gonna be dumb, you better be tough +--------------------------------------------------------------------------------+
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Thanks to everyone for the responses so far.
To give you all more information....
Our small door company produces doors for contractors. We don't do ANY finishing for customers. The doors are final sanded and it's up to the customer to stain/finish them. I DO however try stains from time to time to inspect the sanding quality. Although the suggestions on conditioners and sealers is very good advice.....I need a better final sanding solution to be able to hand off to the customer so they can be ready to stain once they receive the doors with no work having to be done by themselves.
More info on our machines....
The main machine in question is a Unique GT250 and a Unique 336-4 Shape/Sand. Both setups....easily 100k all said with tooling. So as far as the quality of cut....our tooling is carbide insert tooling that is clearly sharp enough. We run the cutters at 7000/8000 rpm's....so speed isn't an issue. And never have we ever been able to cut CROSS/END grain, even when everything was brand new, we could never stain end grain without problems. Even the machine manufacturer agrees that it's not possible....that's the reason we bought the shape and sand machine in the 1st place.
On our shape and sand the feed rate is 20 fpm and the cutters are run ar 7000rpm. The cuts come out fine. With the grain cuts can be stained to a somewhat acceptable level with little or no sanding. But again, the problem is the end grain. For the sanders...the sanding head is with 1000th of an inch match to our cutting profile. We run the sanders at 1350 rpm between 2 stations. The first station hits with 150g and the second with 180g.
Something that is interesting......some have mention going up very high with the sanding on the end grains. I need some more specifics....;
Are you guys suggesting like going to 220/320g or even higher? 400/600g?
Thanks for the feedback.
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Yep. If you are only sanding to 180, would recommend going to 320 on the end-grain. When sanding to 220, I would go to 400 grit. I've never tried sanding at any higher grit on wood than that. It seems to burnish the end-grain and make the coloring come out more consistent with the top and side-grains.

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One last point- Yesterday I had to cut an oak panel and as I was doing so I realized that my early morning response neglected to add one point that might be the reason I don't have problems as you describe. I make multiple passes. The panel I made yesterday was from 5/4 and I made 3 cutting passes and one finishing pass. The final pass is taking out only approx. 0.5-1.0mm... If I was to make this same panel with a single pass I would probably have the end grain issues you describe. I make panels in custom finish work application so the work of three passes is not an issue for me. However, if you are running larger production this might not be practical.
Good Luck!
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What you're doing is heating, stuffing small dust in, and allowing the contracting that goes with the heat and overdrying to close the wood vessels. Their job, prior to your murdering them to glorify your living space, was to conduct liquid over distance. Unless you find a way of putting a finger in the dam, they will.
That's why stuffing with resin - sealers - works.
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End grain will soak up more stain. Because of the translucent nature of stain, the more you put on, the darker it becomes. Flood the end grain with the type of solvent that your stain uses (mineral spirits for oil based etc...) This will decrease how quickly the end grain absorbs stain.
-nick
Here is what I've done.

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Nicky wrote:

This may be true, but only if you are applying it wrong.
According to Bob Flexnor, the correct way to apply stain is to rub it on with a rag and then wipe off the excess in the direction of the grain. This will fill the pores with the stain particles. Once filled, you cannot put any more into the pores.
If you slather the stain on and let it dry without wiping off the excess then indeed it will get darker with each application. It will also obscure the grain as the stain partlces are opaque.
A stain, as opposed to a dye, is a suspension of solid particles in a translucent or transparent base.
Of course according to Bob Flexnor anything that you do differrntly from him is wrong. ;-)
--

FF


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