Restoring Darkened Cracked Shellac Finish on Wood

[phil]

shellac has a low melting temp. I put some old radios wrapped in newspaper and the paper stuck to them .

I'd try lacquer thinners, it might work faster, or acetone , careful its more flamable.

shellac last forever in solid form flakes or cookies, ive got an old chunk like a 1/4 inch thick sheet with a label impressed in it from about the 30's

when you mix it with alcohol a precipitate is formed that white gunk so let it settle and you can pour off the top. you don't want the wax between coats, its a byproduct. I've heard of people putting it in the freezer to speed the process of removing the wax.

if you mix it or buy pre mixed it has a shelf like might not harden right so do a test if its very old.

type of alcohol might matter. I got mine at mohawk and it was labeled shellac reducer. don't use rubbing alcohol. isopropyl alcohol might be ok. we might see tightening of codes for environmental reasons, the alcohol vapors are a pollutant. we used lots in the printing process and they were trying to eliminate it but it lowers the surface tension of water. also drug makers want the stuff. You can dissolve the THC from pot with it and make shatter, kind of like purified hash. this is done because the big leaves aren't very good to smoke so they extract the THC that way to make use of the coarse leaves. I think its used for making hard street drugs too so there may be some vendors watching how much people buy without proper reasons. I know with printing as a supplier we had customers that bought nothing but buckets of alcohol until the management got concerned what they were doing with it.

they put stuff in alcohol used commercially, so people dont' drink it. and I'm not really sure if what they add affects the finishing process. I'd like to know more about it.

one of the highest grades is medical alcohol they use it to sterilize stuff I guess so that's probably one of the more pure ones. probably more prohibited too. maybe its an excuse to build a still honest officer..it's just for my shellac
you can make alcohol from fruits, anything with sugar, yeast grows, produces alcohol, then distill it bu they also can make alcohol with wood that isnt' drinkable. It might be good to know more about how these impurities affect the properties in the finishing process . I think Ive heard some claim it doesnt' matter much and some claim it does. so i'm not completely sure myself.
If you are removing it I think you'll go faster with lacquer thinners, its a stronger solvent. Its different if you are trying to re-amalgamate the finish. also if you use a heat gun itll soften easily.

if its a flat surface a card scraper can work really well. if the surface is flat like a tabletop a card scraper ( also called a cabinet scraper) will make short work of any shellac without any need to dissolve it. There is a bit of a knack to using them properly but once you get it you'll find it the most valuable little tool ever, and its cheap, easy to sharpen yourself, and it'll fit in your shirt pocket.
heres a link to the ones at lee valley
http://www.leevalley.com/us/Wood/page.a ... 10&p=41069

I bought an assortment of thicknesses for fine or rough work , the little holder and the file jig to sharpen it and the tool to burnish the blade. all you really need to buy is the scraper. those accessories are a nice to have.
You can just put it in a vice and sharpen with a mill file. you can burnish with the hard shank of a screwdriver. the holder isn't needed but sometimes it handy if you want to pull towards yourself. if you dont have strong fingers it's a bit easier with the holder. it maintains the bend and you can adjust the amount of bend. when you use it you hold it with two hands and form a bend in the blade and push. when you push with the blade it can get hot as well. I usually sharpen all 4 sides, thats 8 cutting edges, some just sharpen one side for safety.
I roll the corners of it a little so I dont dig the corners in as I go but sometimes you want a sharp corner to get into corners. some put those little plastic strip things like you might use to make a booklet with two acetate sheets, to cover the sharp corners. its just plastic edging you can slip on or off the blade.

if you want to make a card scraper you can cut up an old handsaw with a dremil or a cut disk in a grinder or using a masonary blade. its about the right springiness. If you happen to have a handsaw with a crack in the blade it'll make a few free card scrapers. some handsaws are thicker some thinner so that's an easy source of appropriate blade material if you are cheap like me

Usually its a push tool, that's the most efficient way. first a hand plane to flatten stuff, then a card scraper to fix the imperfections , then sand if you need to .. the card scraper can flatten things better than sadpaper because sandpaper pulls the softer grain out first, the scraper cuts similar to a little hand plane but finer shavings.
i dont find them useful for paint stripping, better to use carbide and a heat gun but they are really great once you are down through most of the paint. You can't use a heat gun in combination with a card scraper or you'll just burn your hands.

with somethign like restoring a table Id use the cardd scraper when im not concerned about removing patina. dont use it if you want to retain the patina and darkening of the wood. usually I find it easier not to worry about marring the wood and just go into fresh wood then darken it if I want it darkened. If you go half way then your scraping efforts can show up as tool marks in your finish.

ive been pretty successful with casings and things like that I just get most of the poaint off then use a belt sander or put them through my thickness planer. that takes a lot off fast, saves work scraping. removes stuff like the cup shape from boards, they end up a bit thin and if I am concerned with that I glue wood strips to the backside to make the difference up. Ill follow the sanding or thickness planer operation with the card scraper to even things out , then fine sanding. I like to sand with wet or dry paper dipped in danish oil and turpentine, then Ill do other finishes over that. I like how it pos the grain and it hardens the surface under the finish so its more durable.

so my process is clean to fresh wood , the sand with danish oil and turps , I do a few coats, then If I want poly or shellac or laquer that I do on top. That's what works for me. If I want darker I sometimes put a tiny bit of stain in the mix but not on the first or second coat thats because the pigments can amplify the tooling marks , scratches suck up the stain so I use clear for the first two coats to seal the wood up and the sanding with that mixture on the paper leaves it silky smooth. this also unclogs the paper so it lasts a long time, and the slurry is driven into any voids it can fit into so it is sort of filling the voids with the fine dust as I do that.

one reason I really like this way is because the dust aroungd the shop doesn't bug my finishing job. im able to sort of pre-finish my wood then if I want to use shellac and things its not dusty and the surface is already pretty nice to start with. easier to do a good finish on a nice surface.
soem cabinet makersa nd refinishers use grain fillers. you can apply it and take it off with a credit card. it fills the voids. then the finish is flat and shiny rather than having the bumpyness of the grain. some do finishes and dont worry that the grain has some roughness. If you rub your finger across the wood it isn't uncommon that you can feel the grain even after finishing. on something like a pianno it might be so flat that it feels like glass. depends what you want to achieve. a pianno finish can be too much and it can show a mark more easily if the finish is that high. so the finish should really match what you are doing. a piano finish isn't what you'd expect on a baseboard for instance, but who's to say whats too much.

[KenN]

Thanks Phil, I dug out one of my card scrapers today and it helps to knock off all of the congealed bumps of shellac and it looks like I can get just about all of the shellac off this way down to clean wood. I just have to be careful to make sure I am scraping shellac and not wood. Quicker than trying to slowly dissolve it off with clean alcohol. The alcohol fumes get to me anyway even though I do this outside.

I have some curved scrapers somewhere, I’ll see how they do on the curves.

[phil]

if you want to make a curved scraper put masking tape on, draw the curve as accurately as you can. use a dremil tool with a cutoff disk or a little grindstone and you can cut the shape to match what you are scraping.

if you had a sample of a molding you can then ink it. put the scraper against the inked molding and see how well the ink transfers to the blade. remove only the metal where the ink transfers, eventually it should transfer right across the cutting edge, then it fits exactly. .
This takes a bit of trial and error. you could wrap the molding with something like tape to keep the ink off it. you can use paint instead of ink but that's probably enough to get the idea across.
another way to see better is to lay a flashlight behind the blade and then you can see the light gap anywhere the fit isn't close.

and then if you want to make molding you can use the scraper to do the shaping work and use a saw to remove the bulk. You can make a little adjustable wooden holder to hold the blade and keep it positioned like you want it. you probably wont make hundreds of feet of molding like this but sometimes you just need a foot of a certain shape or to use the scraper to remove paint or shape fillers.

its surprising but the shape of the blade needs to be very accurate or you'll change the look of the shape of the molding. also when you use a scraper freely you dont hold it square you slant it a bit or it chatters across. You might be able to fine tune the cutting edge a bit or make some accommodation so that you can run it on a bit of a slant. you could make a holder first that fixes the angle in a certain position so when you do the fitting with ink you have a consistent angle.

then when you do sharpen it, you might need to recheck the fit.

you can buy old molding planes that were used to make molding Stanley made one with an assortment of blades and a jig to follow the edge of a board. I have one , seldom use it. some of the older ones were hand made by the cabinetmakers that used them. woodwork is one of the oldest professions so this stuff definitely isn't new technology. nowadays we use routers. The old methods have their place in restoration.

[1918ColonialRevival]

When I reamalgamate old shellac, I always mix a little bit of shellac flakes in with the denatured alcohol. If you are using only alcohol, you are basically stripping off the finish. You want to soften the finish, but not strip it. It's also important to make sure it's clean, otherwise you'll be re-distributing a century's worth of old furniture wax, nicotine, and all kinds of other contaminants into the finish.

A couple of other tips. When you dissolve shellac flakes in denatured alcohol, always let it sit overnight to make sure everything has dissolved. Then, filter it down through a paint strainer before you use it.

[KenN]

Here is what is working well for me now...

I use the scrapers to get as much of the shellac off as I can. The flats are easy, I have some curved scrapers that help with the profiles.

Then I take some 0000 steel wool and alcohol and rub what’s left into a sort of slurry and wipe that off with clean rags.

This is the quickest process for me so far and gives good results.

For now stripping and reapplying new shellac is what I will do. I will try re-amalgamating again in the future. This old shellac seems to be more dirt than shellac.

[phil]

hopefully any scratch marks from scraping won't show. If they do you might need to do some sanding before applying the new finish in order to get rid of any tooling marks. at that stage I usually apply some oil so I can see the grain pop, because sometimes things jump out when you start applying your new finish that you couldn't really notice with the finish off. I find it easier to correct that stuff by sanding it out then applying more oil. You can always wash off your new finish if it isn't looking satisfactory to you. I usually just use the clear danish oil and when I'm happy with the look then I lock it in with my clear finish. the oil does dry and of course I wipe it off after applying. it wont affect the bonding of the shellac or lacquer, or poly in fact you can just do that without applying the shellac if you like it you can build a nice finish that way all on its own.
with an oil finish it will look a bit different and that may or may not be acceptable in a restoration. It does give you the option of doing more coats as maintenance and coating with more oil only takes a few minutes. one problem with shellac and lacquer is that if people spill alcohol on it it can really mess up your finish and people of today aren't really use to using coasters like they were in earlier days. since many tables and things of today have a tougher finish people sometimes don't understand it just isn't cool to put your drink or a plant on an antique table that has lacquer or shellac.

antique restoration should really be about using the same finishes as the aim usually isn't to change things but to make them look like they were cared for.

i wouldnt' use poly because I hate it on furniture I think of it as damaging an antique but a table that kids play at would certainly benefit from a tough finish and the user of the item may make that choice. we are often rough on our coffee table. we play games on it and use it every day. I even do some radio restoration work on it. I dont want a surface that we use so much to be too delicate. I've got a beautiful coffee table my father made and I have it put away because I just dont want to see it all marked up or to try to police how it's used. Ive seen lots of old radios with damaged tops from moisture from plants and it's a lot of work to correct.

i found a vintage ironing board, an old wooden one so we use that as a plant stand.