Sanding between coats of finish?

[Ky-Flinter]

I am in the process of applying Chambers Oil Finish to a birch stock that has been stained dark.  The directions say "Sand lightly between coats."  The stock has both incised and raised carving and the usual corners and edges.  I don't want to sand thru the stain on edges or round off corners, etc. but obviously subsequent layers of finish adhere better to a "roughed up" surface.  Sanding around the details with little pieces of 400 is becoming tedious.

So, what is your technique for this process?

I did a search here and found some info of interest.  One reply stated "A soft toothbrush with pumice and oil in the carving. Make sure you brush it out well when done."  If you use this method, what sort of oil do you use?  And where can I buy pumice or rottenstone suitable for this method.

Thanks for your help.

-Ron

[Jim Kibler]

I wouldn't sand between coats.  Don't think you'll experince any problems with coats adhearing.  You could rub it down with a bit of scotchbrite if you wantedd to.  As with most of these things, just go for it and you'll figure it out as you go.

[Gary Tucker]

Ron, I use rottenstone after my final coat of finish.  I got mine at Woodcraft.  Also got the parrafine(?) oil to use with it.  I use a soft cotton cloth dipped in the oil and then in the rottenstone.  I gently rub in the direction of the grain.  I use a soft toothbrush dipped in the oil, then the rottenstone, and do the carving and mouldings.  I really like the way it softens the sheen, and easy to do.

[Meteorman]

I use Chambers oil and love it.
Between the first 4-5 coats I buff very lightly with 00000 steel wool  - careful around corners and edges as you note.
After every buffing, I use tack cloth and compressed air to clean the entire piece - about 3 complete sweeps end to end each time.
You'll know right away on the next coat if you didn't get all the debris off.

last 2- 3 coats nothing in between.
final light buffing with rottenstone and oiled "rubber" (tightly wadded up lint-free cotton cloth) to knock down the sheen.

/mike

[mjm46@bellsouth.net]

I do pretty much the same as Meteor Man except I add a final coat of renaissance wax for the finish.

[Jim Chambers]

After we started making our oil finish and after I had already had a few thousand labels printed, I discovered from a paint chemist that sanding between coats of this type of finish is not necessary.  When using any type of polyurethane finish it IS necessary to sand between coats, but not the case with our kind of oil finish.  Coats can be applied one on top of another until the desired depth of finish is achieved.  I usually apply one heavy coat as a sealer and then three or four additional fairly heavy coats letting each dry one day between coats.

[Meteorman]

thanks Jim. (both Jims, actually). 
Since you invoked a coatings chemist, I suspect you are addressing the issue of adhesion of subsequent coats, and that no "roughing up" of the previous surface is needed for good adhesion of the on-going coat.

I find that in the rubbing-in process for the first few coats, I often have a few wood whiskers pop-up, and I do the light steelwool treatment to knock them down.  After a few of those passes, it stays pretty dang smooth.

That's probably an indication I'm not doing an adequate job of de-whiskering in the first place.

/mike millard

[bgf]

I like the green scotch brite pads (from the kitchen -- just make sure they're not the ones with detergent) between coats after 24 hours, then wipe carefully with mineral spirits or similar.  Seems to make the next coat go on more smoothly.  If using something that can do more than one coat a day, I sometimes just rub with a coarse paper towel (the finish will be "dry" but still quite soft).  The "sanding" gives the previous coat some tooth so it can hold the next coat; I trust the chemists (and my own experience) that adhesion is no problem, even with a polyurethane component in most cases, unless possibly if the finish is completely cured (usually well after 24 hours).  Of course, if you have a drip or run or dust spot (probably just me that has those problems), sanding that out is fine any time between coats. 

[Dr. Tim-Boone]

thanks Jim. (both Jims, actually). 
Since you invoked a coatings chemist, I suspect you are addressing the issue of adhesion of subsequent coats, and that no "roughing up" of the previous surface is needed for good adhesion of the on-going coat.

I find that in the rubbing-in process for the first few coats, I often have a few wood whiskers pop-up, and I do the light steelwool treatment to knock them down.  After a few of those passes, it stays pretty dang smooth.

That's probably an indication I'm not doing an adequate job of de-whiskering in the first place.

/mike millard

Another way to prevent whiskers is to seal with a 1# coat of dewaxed shellac, sand back to bare wood, bone or burnish the stock and then apply Chambers oil  ... adds some color if you want and slows the ab/adsorbtion of humidity too

[dannybb55]

I wonder what E K does?

[keweenaw]

A lot of that surface texture - whiskers, etc. can be burnished back into the wood.  After that first really heavy soaked in coat of Chamber's finish but before it's completely dry I heavily burnish the entire stock with a steel burnisher.  Smooths things right out.  I've found that the time to use the scotch brite is after the AF and stain but before the finish goes on.  Because the AF is changing the color of the wood and not putting a color on the surface like a traditional stain one can smooth things out without much effect on the color.

Tom

[Jim Kibler]

Since the topic has diverged a little from abrading between coats for finish adhearance to smoothing the wood surface, I will add my latest experience.  I've tried many different methods, sanding and repeated grain raising, scraping, burnishing after sealing, sanding or scraping after staining, etc.  On the last gun I finished it was primarily scraped and I didn't bother to raise the grain. I applied one coat of ferric nitrate (aqua fortis) and heated.  At this point the stock was pretty rough as you would expect.  I then applied a second coat with some marone scotchbrite, scrubbing the stock pretty heavily in the process.  This smoothed the stock very well.  Even after heating this second coat the stock remained quite smooth.  I then sealed and burnished the surface pretty hard with a polished antler.  I'm quite happy with the results.  Applying the aquafortis with an abrasive pad is something I'll remember.  Worked extremely well.  I suspect with experiementation a historically correct material could be found to replace the scotchbrite. 

[bgf]

Jim,
That is an interesting technique.  I found that vinegar and iron and then LMF stains also raised the grain a bit even after de-whiskering the bare stock, but the green pad after staining smoothed it out nicely again, and didn't change the color much -- might have lightened it a little.  Maybe applying those stains with an abrasive pad would work also, two birds with one stone .

[Meteorman]

thanks Jim.
I'm about 1 week away from beginning the stain and finish process on my current build, and will try your technique as described above.  I even have a polished antler ready to see action.
/mike

[Dennis Glazener]

I have mentioned this before, in high school our Industrial Arts teacher did his thesis on wood finishes. He taught us to make a thin glue using floor/water not sure what else, long time ago! Anyway we brushed it on let situp over night then sanded off the stiffened whiskers. Kept doing it until no more were raised. I tried it with watered down wood glue seemed to take care of the whiskers after a couple of applications.
Dennis

[Dphariss]

There are a lot of somewhat strange things advocated in stock finishing.
After about ww-1  (or maybe even well before) is seems everyone forgot how to do stock finish. Part of this was the result of factory made rather than shop made finishes, many of the factory made finishes did not work well on gunstocks. So all sorts of weird and sometimes very labor intensive processes cropped up all through the 20th century.

If the maker wants the grain raised then RAISE THE GRAIN. Plain water and a hair drier "gun" works just fine. Cheap at yard sales.
I will raise the grain with every grit of final sanding from 150 up to 320 or 400 depending. Better sanding and grain raising can save a LOT of time in finishing.
If grain raising is not wanted then don't. Its possible to stain a stock with AF, oil it then burnish while the finish is wet to glue down the whiskers. Or so I have been told.
Given how old wood working was by the time the flintlock was invented I really doubt that gunstockers did not know that whiskers could be removed with a little water and elbow grease. I just don't know the process. I suspect even careful scraping would work.
AND a fairly heavy bodied oil varnish will cover and smooth many imperfections in the stock, scraper marks etc so the finished gun could be carefully scraped than varnished, probably one coat and the rifle would be ready for use in a day more or less depending on the weather.
But this will not work with highly thinned modern finishes.
This could very easily be why varnish was popular, but again remember that varnish then is not necessarily varnish now. If linseed oil was cooked with dryers so it would dry to a shine it was "varnish". So even soft, by modern standards, oil finishes would be called varnish.
Very hard varnishes of the time were hard to make and used expensive resins and had little advantage in firearms and may actually have been a poorer finish than the cheaper softer varnishes.
Dan