# Glass scraping



## jsdonaldson (Apr 4, 2012)

hey guys. I've got this table ive been working on for quite some time. I really want this piece to stand out and be nice since i started it senior year in high school (im 20 now) Well i got the top all done and sanded all the way down to 400grit. After sanding i cut some small pieces of glass to scrap the surface because i heard you can really bring out the character of the wood if u use this method for final sanding. I am actually impressed with how the wood pops after using the glass. The only problem is i am left with some lines from the scraping which are only visible with certain light angles. I was wondering if there is a way to buff the lines out before i apply the finish without remove the results of the glass scraping. or will these lines just disappear when i apply the finish? thanks for the help. i will post some pics.


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## chemmy (Dec 13, 2011)

Sorry, that's really a "myth-understanding", even a metal scraped surface or other will not give you more refraction in the sense of when coated it will look more so than if just sanded and coated. In fact that's all it is doing is giving you a better visual refractive index N/d while uncoated, If you were to have polished the wood to 600 or 1000 grit paper you could have accomplished the same N/d without all of the un-levelness of the surface the glass scraping has caused. 

Try going back to like 180 then 220.320/400 again to rid the waves and scratches and then if you must, go to 600/1000 grit, although it's really not necessary. Be careful not to cut through the veneer, if it is veneer, in doing so ok?

What is going to give you your best N/d will be the solvents and resinous material used over the wood!! The closer their N/d is to the woods, the deeper and more brilliant the wood will look, bringing out any figure or other highlights it contains. 

For me that would be a mixture of 10% polymerized tung oil [N/d 1.53 and 90% pure gum turpentine [N/d not necessary due to evaporation, used for better penetration of the oil] When dry, then you can apply shellac/nitrocellulose lacquer/acrylic/polyurethane or most any other coating being sure if it's water-base to seal with shellac first as a barrier coat between the oil and final clear coat of choice ok?

PS: i don't know how old your info was for doing the glass scraping, but back at the time when steel or glass were used that was pretty much all that was available to those who did so, sandpaper even then was expensive in comparison, it was a poor mans way of trying to smooth the surface so to say.

Even then the glass edge or metal that was used, had to be a flat plain with no chips or curvature [unless scraping a curved surface] to have had success in providing a "smooth" flat surface on the wood ok? Even when using a card/metal scraper today that still holds true. With metal it is not very difficult to do, but with broken glass.... yes! Even on a freshly cut perfectly straight piece of glass cut with a diamond glass cutter you will see [under magnification] that on the cutting point of the edge there are chips and or irregularities.


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## jsdonaldson (Apr 4, 2012)

ok thanks for the input. It's actually not venneer, it is solid. Purple heart, maple, and mahogany. even the thinnest parts are almost an inch think.


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## chemmy (Dec 13, 2011)

jsdonaldson said:


> ok thanks for the input. It's actually not venneer, it is solid. Purple heart, maple, and mahogany. even the thinnest parts are almost an inch think.


 
Good to hear, then you have plenty of room for correction, i would then suggest starting with 150 grit to insure you have leveled the surface marks out completely ok?

Have fun!!

Chemmy


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## woodnthings (Jan 24, 2009)

*question..*

Are the marks raised ridges or depressed in the surface? If they are raised, wouldn't it be easier to use a card scraper and just lightly skim the surface? :blink: bill


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## chemmy (Dec 13, 2011)

woodnthings said:


> Are the marks raised ridges or depressed in the surface? If they are raised, wouldn't it be easier to use a card scraper and just lightly skim the surface? :blink: bill


Hey Wood, what are you diong up this early, lol

Pretty sure from the one pic there deep into the wood, but your correct if it is the opposite. If your like me and hone and polish your scraper to a fine glossy edge [8000] grit before making the burr, then you can get wonderful results as to smoothness. Extremely thin shavings and curls.


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## cabinetman (Jul 5, 2007)

jsdonaldson said:


> I was wondering if there is a way to buff the lines out before i apply the finish without remove the results of the glass scraping. or will these lines just disappear when i apply the finish? thanks for the help. i will post some pics.


The grooves are likely into the surface. But either way, a leveling by sanding would be necessary to get it all flat, and removing enough wood. The problem is, that with starting with 150x to 180x, which is what will do that is to only sand with the grain direction. With all those transitional meeting members, it will be tedious to do that by hand. You certainly don't want cross grain sanding to appear at this stage of finishing.

You might consider using a random orbit sander (if you have one). When you get to the finer grits...220x - 320x or finer, you could use an open coat sanding disc. Or, if you leave a 150x sanding disc on the pad, place a Scotch-Brite microfiber pad to it. It will stick like H&L (hook and loop)...something like a Velcro arrangement.

*Scotch-Brite colors equivalent to sanding grits**.*










 







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## Icutone2 (Nov 4, 2011)

Thanks for the info sheet!
Lee


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## HowardAcheson (Nov 25, 2011)

Let me say that while you have created a nice looking panel, you are probably headed for trouble. You have a number of cross grain joints. Wood expands/contracts across its width. The end wood joints glued to long wood surfaces will try to prevent the expansion/contraction of the end grain wood. This will lead to cracking or splitting or failure of the joints when there are changes in relative humidity. In addition, your frame will also try to prevent the expansion and contraction so it too will fail.

If you have very stable seasonal relative humidity you may be lucky.

Let me suggest that buying a book titled Understanding Wood by Bruce Hoadley would be a good investment. It will give you all the info you need about wood and its properties.


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## cabinetman (Jul 5, 2007)

HowardAcheson said:


> If you have very stable seasonal relative humidity you may be lucky.


In a stable environment, it may not be at risk.








 







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## jsdonaldson (Apr 4, 2012)

HowardAcheson said:


> Let me say that while you have created a nice looking panel, you are probably headed for trouble. You have a number of cross grain joints. Wood expands/contracts across its width. The end wood joints glued to long wood surfaces will try to prevent the expansion/contraction of the end grain wood. This will lead to cracking or splitting or failure of the joints when there are changes in relative humidity. In addition, your frame will also try to prevent the expansion and contraction so it too will fail.
> 
> If you have very stable seasonal relative humidity you may be lucky.
> 
> Let me suggest that buying a book titled Understanding Wood by Bruce Hoadley would be a good investment. It will give you all the info you need about wood and its properties.


I appreciate the input but i beg to differ on the fact that i'm headed for trouble although i could be wrong. There is the possibility that my wood shop teacher in high school didn't know what he was talking about and simply set me for failure by suggesting the currently used methods for the construction of my table. You seem to insinuate that i dont know anything about wood working by suggesting this book. granted i dont know anywhere near as much as some but I'm learning. i just think this goes a bit beyond the scope of constructive criticism. It shows no signs of expansion or warping so far. I live in Montana where the humidity stays low throughout the year. I've seen many high end tables constructed in a similar manner and they didn't seem headed towards failure.


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## chemmy (Dec 13, 2011)

It's hard to argue with the fact that the table has been stable over 2 or more years unprotected. It's also very possible your shop teacher had read The book suggested and knew such to begin with. I believe reasonable expectations would be for very slight changes in the EMC of the table over the lifetime if contained in the same region. There would only be concern if moving to a locality with a much greater humidity or lack there of to affect it in a large way. 

Though i do think that both of Bruce's books are of great value and worth the read and knowledge contained, They contain little that could not be gleaned for free from the national forestry archives of things of this nature and most everything else.

US FORESTRY "WOOD HANDBOOK" google.


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## jsdonaldson (Apr 4, 2012)

chemmy said:


> For me that would be a mixture of 10% polymerized tung oil [N/d 1.53 and 90% pure gum turpentine [N/d not necessary due to evaporation, used for better penetration of the oil]


Well today i went out and bought a can of Formby's High Gloss Tung Oil Finish as well as a can of turpentine. Now I know this is not pure tung oil as it is a finish but do you think it would still be good to use? if so, should i still mix a 10/90 solution with the turpentine or a different mixture or not at all? thanks for all the help.


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## chemmy (Dec 13, 2011)

jsdonaldson said:


> Well today i went out and bought a can of Formby's High Gloss Tung Oil Finish as well as a can of turpentine. Now I know this is not pure tung oil as it is a finish but do you think it would still be good to use? if so, should i still mix a 10/90 solution with the turpentine or a different mixture or not at all? thanks for all the help.


It will work but not as well as pure poymrized tung would, look at southernland wells on line and get back, don't open your materials ti l then ok?


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## jsdonaldson (Apr 4, 2012)

I see. Went to their website,it is really nice. Which one of their tung oils do you reccommend? Original?


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## chemmy (Dec 13, 2011)

jsdonaldson said:


> I see. Went to their website,it is really nice. Which one of their tung oils do you reccommend? Original?


The original is good, but i prefer the exterior solvent based not citrus based, if i need to cut it further i use the pure gum turpentine for better penetration- first coat usually the 9 t0 1 ratio of oil to turps. It may be overkill since its not exterior, but the extra uv protection never hurts.


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## jsdonaldson (Apr 4, 2012)

so what would happen if i used the regular as opposed to the exterior? would the uv rays eventually yellow the finish? Does the exterior stuff still offer the same amount of clarity?


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## chemmy (Dec 13, 2011)

jsdonaldson said:


> so what would happen if i used the regular as opposed to the exterior? would the uv rays eventually yellow the finish? Does the exterior stuff still offer the same amount of clarity?


J, there all good, the original loclamin finish is what i used first and most, up till 2005 i had a small walnut burl dining table i did in 1992 that still looked excellent. If you would rather go with that it won't be a mistake, the offer of using the exterior was my thought on the lighter wood ambering out to where you might not like it but that would be many years down the road, and yes the uv will slow that down more than the original but will not keep it from happening indefinitely, for the you would need another product called HALS [ hindered amine light stabilizers] that you could actually apply to the bare wood to stop lignin decomposition and discolouring. Unfortunately it's not available to the general public or if it is i don't know by who. Still even with that, the oil will eventually amber. 

The only other thing i can suggest is acrylic coatings that will never amber and stay crystal clear.


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## jsdonaldson (Apr 4, 2012)

So after applying the tung oil (many coats) it would be good to use a shellac to seal it and then go over it with my clear coat? I plan to use a guitar clear coat and a buffer to get a nice glossy look. Does this sound fesable? I know im asking a lot of questions but you have been a tremendous help and these questions can potentially save me a lot of trouble.


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## chemmy (Dec 13, 2011)

jsdonaldson said:


> So after applying the tung oil (many coats) it would be good to use a shellac to seal it and then go over it with my clear coat? I plan to use a guitar clear coat and a buffer to get a nice glossy look. Does this sound fesable? I know im asking a lot of questions but you have been a tremendous help and these questions can potentially save me a lot of trouble.


WOW, sorry J, i didn't realize you wanted a guitar type finish as a final look, no, in that case i would skip the oil altogether and also wouldn't use the shellac, i would just build with the guitar finish as many coats as i needed. Is it a lacquer/2K poly/acrylic or other?


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## jsdonaldson (Apr 4, 2012)

well quite honestly i dont know what i want. ha ha. I really like tung oil finishes but i like the protection of the clear coat. Is there a way to do a tung oil finish and then cover it with something or is it not possible to get the best of both worlds? i really want to bring out the character of the wood. but i also want to protect it from phisical damage.


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## chemmy (Dec 13, 2011)

jsdonaldson said:


> well quite honestly i dont know what i want. ha ha. I really like tung oil finishes but i like the protection of the clear coat. Is there a way to do a tung oil finish and then cover it with something or is it not possible to get the best of both worlds? i really want to bring out the character of the wood. but i also want to protect it from phisical damage.


Ahhhh..... the search for the perfect storm huh? Ok, lets go over some things ok?

"physical damage" is going to happen no matter what coating you use, nothing is bulletproof, not even polyester or epoxy in fact, not even glass. Though if they made a low temperature sprayable glass coating the would actually adhere to wood, i would be the first to recommend it lol. :laughing:But..........they don't.

of course you can easily prove me wrong by keeping it locked up in a bulletproof glass room with 24 hour guards, But if used and in an arena where peple/pets/or kids are present, it's gonna happen lol. 

Next i hate to see you invest the money for just one application of tung cut even further with turps to bring out any figure your top has, from what i can see there's a little but not much, if it were highly figured woods like curly or quilted maple and burl walnut and bees-wing eucalyptus, then i would say GO FOR IT!! 

What you can do however is severely dilute your coating [5% coating to 95% diluent/thinner] or even better if it's acrylic replace 20% of the diluent with retarder and let it all soak in and dry overnight, and then use normal coats to build with over that, acrylics N/d is also close to woods. you will get a good look and surface protection that way, but as noted no guarantees as to damages. Seen any older used guitars played often in quintessential condition? lol. 

Hope this helps J, in making up your mind, the only thing left open at this point is your preference of coatings - you can also do the same with a top notch 2K which has better damage resistance but cost a lot more also.


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## jsdonaldson (Apr 4, 2012)

what would you do if you were in my shoes? whats your fav finish for a table?


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## chemmy (Dec 13, 2011)

jsdonaldson said:


> what would you do if you were in my shoes? whats your fav finish for a table?


well if i were in your shoes and money wasn't an object i would go for the 2K poly. If i didn't feel it warrented the expense, then for sure sherwin wiliams catalyzed acrylic instead. That's all the choices i'm giving you.......:laughing:


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## jsdonaldson (Apr 4, 2012)

what if i were to do the base coat with tung oil, then 8-10 coats of minnwax wipe on varnish, then finish it all off with a natural beeswax and a good polish? You think it would look good?


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## chemmy (Dec 13, 2011)

jsdonaldson said:


> what if i were to do the base coat with tung oil, then 8-10 coats of minnwax wipe on varnish, then finish it all off with a natural beeswax and a good polish? You think it would look good?


Hi J, Skip the beeswax just put on more poly if that's the route you want to go ok. BW even when polished out nicely smears up to easily and does not look good. To delicate better to have ahard smooth surface


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## cabinetman (Jul 5, 2007)

jsdonaldson said:


> well quite honestly i dont know what i want. ha ha. I really like tung oil finishes but i like the protection of the clear coat. Is there a way to do a tung oil finish and then cover it with something or is it not possible to get the best of both worlds? i really want to bring out the character of the wood. but i also want to protect it from phisical damage.



Deciding on a finish can be a tough decision. You didn't say whether you have the ability to spray a finish (spray gun/compressor). If not and you are planning a wipe on finish, you can get very good results.

If you are planning a wipe on, since you already have the Formby's, that can be a stand alone finish done with wiping on. You could topcoat that with a oil base varnish or oil base polyurethane.

Or, you may get more appearance from the wood with a thinned version of BLO (boiled linseed oil), and then topcoated with the clear film finish. BLO may add an amber tone, so try this sequence on a sample.

If you get a sufficient build, it can be wet sanded to a high degree of abrasion, and rubbed out to a high gloss. Here is an example.










 







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## jsdonaldson (Apr 4, 2012)

that really looks nice. Will Lacquer stick to shellac? cause if so i might use a shellac in-between the tung oil and my lacquer clear. BTW i used some of the Formby's on a scrap piece of purple heart, i really like the appearance of tung oil.


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