Removing Old finish

[Spreyton22]

Hi everone,
What is shellac like when it is sand-papered off ?
We have beeb renovating an old blackwood dresser, and the finish has sort of come off in balls of gum - does this sound like it ?
The wood has come up very nicely - I'll post a picture soon !

By the way, we a re new here, and te forum seems great - very informative and busy !

cheers,
Stephen and Karen

[durwood]

the quickest way to tell if it is shellac is to wipe metholated spirits on it, metho is the solvent for shellac. No other normal finsh will be dissolved by metho

[Spreyton22]

Ok - I'll try that if we can find a bit that is not already sanded !
I just seemed strange the way in which it sanded - formed balls and clogged the paper up.
I'll have a good look tomorrow and get back to the forum.

Stephen

[Auld Bassoon]

Doesn't sound like Shellac...

[Spreyton22]

Ok - sorry haven't got around to asking Karen about the exact description - will do later !
Here's a couple of (bad) pictures.

[Flowboy]

Hi and welcome Speyton, (does the spey bit have anything to do with the moggy?)

If the finish is gumming up and balling on the paper, wouldn't it be more likely to be a poly type finish? Its hard to tell from the pics.
What grit and sanding method are you using?

Regards

Rob

[Spreyton22]

Spreyton=Suburb we live in !
I'll get back later about the finish.
Cheers

[Spreyton22]

Oops - got it completely wrong ... (again)

The real story is - when the wood was being sanded the discs became covered with glassy areas some up to ten cent piece size down to really little circles. Karen ended up having to replace the discs much more frequently than usual as these glassy areas built up so much that the gritty parts weren't coming into contact with the wood any more.
Any ideas as to what this finish would have been...plus water damage to the top of dressing table has seeped down along way into the lower parts, so even after much sanding there are still blackish areas and water mark rings!!!!

Hey Guys, it's Karen here...this is such an awesome site. It is so active and thanks ever so much for the feedback and advice. Plus it's so nice to know that we aren't the only one's that bugger the job up now and again!!!! Cheers to all.:)

Oh, also, with sanding the dressing table, I used the orbital sander with a 120 grade disc...bit scared I was going to end up with little squiggly circles that I couldn't end up gettting out. Then went to 180..then hand sanding with 150, 220, 325, 400, 600 and finally 1200 and 0000 steel wool. My arms are officially dead the surface is sooo smooth but the water marks are still a problem!!!

What can I do???

[Flowboy]

Hi Spreyton and Spreytonette (I assume),

Karen, what type of Orbital are you using? You should be able to get all those grits you mentioned as pads (and then some.) If you have a finishing sander, you could put the papers you used directly on to this and still avoid the scarring produced by the previous grits. As far as the watermarks go, some of the guys in restoration may be able to help. Or you could try emailing U-Beaut or consult a local restorer.

Regards,

Rob

[Sturdee]

Sounds like it was some kind of lacquer.

I would have used paint stripper and a scraper to get rid of most and then after neutralising the wood of the effect of the paint stripper with metho some hand swanding to go through the grades for a smooth finish.

How big are the water stains? Is it worth scraping and sanding to remove them ?


Peter.

[rowie]

the discs gum up when the friction of sanding melts the shellac and it becomes sticky. just bang those clogged discs agaainst the edge of the bench and the bally bits will flake off so u can get a little more use out of the disc. when it clogs up again, repeat.i normally scrape as much of the shellac off (with a steel ruler if u dont have cabinet scrapers)before i go anywhere near it with with sander, and only need to start with p240 to try and keep some of the patination(age) in the peice.
be very careful about wetting/stripping old peices as it may warp,split,buckle, and darken the timber considerably.

[JB]

Those water marks and blackish areas could be 5, 10 or even 15mm deep. Sanding them out could take weeks, especially as you work through the grits all the way to Fine Steel Wool...!

What you've already done will have made them less obvious, and I'd say it's now time to refinish the piece. A few marks here and there add character and tell the story of the blackwood dresser.

[Spreyton22]

To every one who has responded to my questions....you all sound like absolute troopers. Thanks so much....we both are feeling much the same as many have said....leave these age, wear marks alone now. At least with all my TLC it's gonna look better than it did before!!!

Cheers
Karen
PS No Sprey has nothing to do with the pussy cat!!! Just a small little town on the NW Coast of Tassie.

[Hickory]

Here is a simple finish test that I have used often.

Working a few drops of boiled Linseed oil into the wood in an inconspicuous spot. If the oil is absorbed, it is an oil finish. If it beads up, it is a hard finish.

What kind of hard finish?
Rub some Acetone into the finish....
If it Sheds like water, its Polyurethane.
If it dissolves in 30 seconds with some rubbing, it's Lacquer.
If the finish turns into a sticky gel, it's varnish or shellac. To find out which, take a cotton swab dipped in Denatured Alcohol and apply to the finish. If the finish dissolves quickly, it's Shellac. If the reaction is slow, it's Varnish.

Of course this doesn't include Water Borne finishes, I'm not too sure on how to approach them, except I know Alcohol dissolves to a certain extent. Anyone got a fool proof way of identifying WB?

And.... you guys don't seem to be accustomed to "Denatured Alcohol" which in the States is mainly Ethanol in which has mixed Methanol in order to make it Undrinkable

[Clinton1]

Did you use the steel wool on the bare timber? The trouble with this is that the steel wool can break off and embed in the timber - later on it can rust and leave rust staining under the finish that you will apply later. Steel wool is best for cutting back a finish, not for using on bare surfaces. Probably get away with it on blackwood though.

Sanding down to 1200 might be a bit too far for this - depends on the finish you go to later. The finish will cover the timber, and you will feel the finish, not the timber. This is especially relevant if you use wax over a finish - you'll feel the wax instead of the timber surface. Besides, sanding sucks!

Did/are you going to use a Ubeaut "sanding sealer" to raise the grain and to allow you to give a final & light sand prior to finishing?

Sorry if I'm bringing up points that you already know. :o

[Justin]

G'day Spreyton(s),

For what it's worth, a couple of tips re. your orbital sander :

- On the topic of clogged discs, try hooking up vacuum extraction to your sander. Usually you can do this by cobbling some kind of fitting up to the port where the dust bag goes. If you don't have a dust extractor, one of the Triton dust buckets paired with a cheapo secondhand vacuum cleaner will work quite well. You'll be very pleasantly surprised about how much additional life you can get out of the discs with extraction in place (which justifies the expense of extraction).

- On the topic of swirly marks (aka swirlies), if your orbital has variable speed try playing around with the speed, probably upwards compared to what it's set at now. Swirlies are a fact of life with orbitals, but you can minimise them with appropriate disc speed and hand pressure for the type of timber you're sanding. Vacuum extraction will also help, as you won't have crap stuck to the discs which will leave scratches in the surface.

If you're looking to do a bit of sanding in the future, and your orbital doesn't have the ability to hook up extraction, or variable speed, then I'd be thinking about getting another one if I were you.


Cheers,


Justin.