Refinishing wood floors with shellac ?

[phil]

thanks for the clarification Al,
Maybe I was confusing it with fiberglass, It too comes waxed and dewaxed and if it has wax you can't recoat without sanding first or it won't stick, But You are right in that shellac is a finish that melts into itself in a similar manor to lacquer and unlike oil based paints or poly.
I don't know any reason in finishing why you'd want he was in shellac to stay in but maybe there are reasons? I just figured it's an impurity that comes along for the ride with the flakes and it's not an additive. Ive heard of people putting it in the freezer to hasten the precipitation.

[Al F. Furnituremaker]

Interesting about the freezer.

I don't know anything about fiberglass, except for what you just taught me. ☺

[phil]

i'd always seen dad using shellac to french polish. I have a few of his pieces and they have stood up well over time.
I noticed on Wikkipedia it said you'd get a much harder surface with shellac if you put it on in thin layers, and I remembered someone saying they just basically painted it on the floor with a brush.
So if it melts together with successive coats Im not sure why it would be harder or tougher or exactly what is happening there. Obviously laying many many micro thin coats on with the french polishing method produces a very thin and shiny finish. not sure why this affect hardness? maybe there is more going on there at a molecular level?

It leads me to wonder if you can put the finish on the floor with a padding technique? or fix your floor that way.
I have tried a little french polishing , I found it easy but I was just doing simple items and I could see how it would get way harder when you had many surfaces and corners and things.
french polishing was a trade. the concentration and how much alcohol is important to build the finish. you are basicly melting the new stuff on top but it is sort of both an additive and removal process and the speed and pressure and how wet the cloth is all come into play. go too slow or get the rag too wet with alcohol and it can stick and muck up whats down. Maybe Al has done more french polishing.

I have a kitchen table with a shellac finish. i made the error of laying a cap from a bottle of alcohol on it and my girlfriend noticed a white spot and wiped the finish right off in that spot so it now has a silver dollar size light spot and she's worn the finish away making bread and stuff so I better not complain I have been thinking I could likely just clean it and do more coats. it's oak and used every day so I wouldn't try to do a perfect finish but it needs something.

If I put a hot coffee cup on it sometimes they stick to the table. we had a beautiful french polished table my dad had done and left a glass candle holder unattended and the candle burnt to the holder and got the glass hot and it left quite an impression in the shellac. I put an old radio in my attic and carefully wrapped it in newspaper and it got so hot in there that the newspaper stuck to the shellac so it has it's drawbacks.

I used oil then poly on my floors. I like them , they are hard wearing but one thing I would say is because they are fir, they do dent and Ive been sometimes dissapointed when peole drop stuff and damage them. maybe shellac would be more forgiving in this way but obviously it's softwood and it will dent and it can't remain perfect. i did my stairs in only dainish oil and I found they wear well too and I kind of like that you can just apply more. I figured poly would be too slippery on the stairs but they are pretty smooth anyway.

on antiques it's common to see this really roughened finish where it goes sort of "pebbly" is this because the shellac got hot from being in the sun inside a window or is it just something that happens over time? often it's patina and not really something to repair. I don't' see this on lacquer so much, I think it's more with shellac finishes.


Phil

[Casey]

If you are doing textbook french polishing, you are using some kind of oil as a lubricant. That oil allows you to keep going long after an oil-free shellac padded-on (which is also a great way to work) has had to call it a day.

[phil]

would that be like tung oil or linsed oil? or something else? Ive never heard that but maybe it would slow down the "sticky" stage and allow more wiping. This is interesting and I'd like to experiment more when I get some time to fiddle with it. also restoring lacquer finishes without removing them completely is a similar technique that would be great to master. Ive tried and usually my result is wiping at least most of it off but it's possible to re-amalgamate crackled finishes and such, but there is a lot of technique to this.

[Casey]

Mostly mineral oil. I have used linseed oil too, and am somewhat convinced that is somehow bonds with the shellac and makes the finish more elastic and water-resistant. Whereas mineral oil just evaporates in time.

[phil]

I use mineral oil when working with some sticky glues and things. if I don't want to wear gloves it makes cleanup easier. .
that makes sense. It's pretty common to add danish oil to polyurethane, I guess that's sort of similar.
Some interesting comments here on that :
http://www.sawmillcreek.org/archive/ind ... 59862.html

Phil

[Duffy666]

All I know about shellac is that I bagged it at a manufacturing plant one summer when I was home from college. Thanks for the education all. Old House Lady and I will be going through this thread numerous times soon! We are suppose to close on the house soon.

[matt123]

This is very useful.

[phil]

it might be possible to remove existing wax with solvents prior to any recoating.

my floors are fir and were quite damaged so needed a fair bit of sanding. then I used poly because I want it to last the rest of my days. I filled many gaps nail holes and really worked the finish. the last coat was satin gloss. I like it like that my floors could not take another deep sanding. another school of thought is maybe they will last longer if you never sand them. It might be an option for some.


Poly is not hard to recoat, it just needs a scuff sand first its a lot tougher finish. Its been around for a long time so it isnt' a new finish , maybe the water based stuff is new. oil based poly has been around 80 years or so and it has been the most often used finish since it's invention. most of our homes are over 80 and will have shellac.

a good point was made , the shellac does reamalgumate so that isnt' going to mess up the bond. shellac and lacquer melt together whereas poly or paint does not and each coat is separate from any prior coats.

The OP was asking about waxing. I dont see anything wrong with waxing the floors. I'd stay away from silicone sprays though, for example pam spray, armorall or some furniture polishes some auto polishes.

the silicone can cause issues with new finishes and can cause fish eyes. I was recently reading that some newer finishes have some tiny amount of silicone in them and that this content actually prevented the issue and that a fix for the problem of the fish eyes could actually be to add silicone to the finish in a very small percentage. I guess its an effect created by issues with surface tension.

if you mop up and dry down I dont think you will harm your finish Just dont let the water stand on it. damp swifter or mop and rung out cloth is ok. I wouldnt use a mop that is soaked but damp is ok. a flood can cause the wood to expand and buckle but dont be scared to wash the floor and dry it up right away. shellac can take that. cat puke might not be an issue cat pee on the other hand will go in the cracks and stay there if the cracks between boards are open.

sometimes old floors have big cracks. I filled most of mine and just left some for expansion and contraction to happen. another way to damage your floor is by getting your mop hooked on a splinter and pulling a big splinter out. If that happens glue it back straight away. maybe is is easier not to do that with the old on your knees method. since I took the time to fill most this has not been an issue but often when people sand and recoat and do not fill the cracks what happens is the edges of the crack become sharp corners. I guess when the floors are old and have cracks they also have some rounding of these corners but sanding sharpens them sort of like an ice skate is sharp and square. socks can get hooked.

its also good to be aware that some woods like fir and oak react with iron so you may see some things like iron nails causing black marks due to the reaction between iron and the wood. If the floor can stay dry it wont happen again, If you have a floor that is a bit porous from age and you put something metal like a coffee can down where there is also water then you can get a serious mark as the iron combines with the wood. the finish prevents this reaction.
my kitchen origionally had a jute backed flooring but what that did was trap moisture and that caused such serious black marks from the nails that I had to use wood bleach on the entire floor, and then use colorants to correct the area which I lightened by using the bleach. I also had lots of patches some plywood areas so I needed to do some serious patchwork , so not sanding was not an option.

most kitchens did not have only wood because the cracks cant' be cleaned and it caused a sanitary issue so they used things like lyno in kitchens. After poly was invented it changed that since then they are plastic coated basically. the building codes may have changed or maybe some of the earlier houses predate such building codes. that point might need further clarification. I dont think the canadian mortgage and housing corportation ( which was tied to new house loans here in the 50's and 60's boom.) allowed wood floors in kitchens and they were then lyno usually. this may differ by area but the point is that a wood floor in the kitchen isn't as sanitary because it cant' be cleaned properly, so it might not fly for example in a commercial kitchen to have a wood floor. I think laminate is now common in houses but its a different animal. If you take things even further than poly one could also go to epoxy which is even tougher yet but also more expensive to apply. you can also use commercial finishes like the buffing machines use in commercial buildings. with that they can build up a thick layer of impervious material and they also strip and redcoat finishes, so those floors really don't get touched by anything because they have such a tough shell in the form of the finish.
of course the more finish that you have on top of the wood , it changes the depth of the finish and finishes like oil or french polish look really the nicest because they dont put a thick shell over the wood.

a very simple option if your floor is shellac and a bit worn and scratched may be to apply danish or linseed oil. where the finish exists it is non porous so when you dry down with clean dry cloths it will all remove, Except in the little scratches and marks the finish will stay in and help hide them and perhaps that would be a way of just making things look a bit better without really affecting the ability to refinish later. use clear not colored or it will collect pigments in the voids and enhance the scratches. almost all of it will be coming back off but it will hide those whitish marks and that's really what shows usually. dont expect the oil to adhere where there is finish , and dry it down to make sure it doesn't try to you arent' trying to build the finish over the shellac, it isnt' compatible but it wont stop adhesion later.
I think they used to apply the paste waxes but also every once in a while they used a wax stripper to remove other layers of wax and then buffed them again. I assume the dirt can get trapped in layers of wax if you allow that to happen. you still see the machines floating around, now pretty much obsolete.

I was watching a guy doing a store, he arrived with this big propane powered machine to apply the commercial wax to the asbestos tile floor It struck me as too serious for a house but maybe if someone did their kitchen with that stuff it would be really durable. It would be a bit absurd in other areas I think but because kitchens do see a lot of wear maybe it is sort of practical. most finishes dont really avoid denting, like if your floor is fir and you drop a can of soup it will leave a mark. oak is tougher.