stripping wood DIY with caustic soda?????

[Deansplit]

I need to strip 80 balusters in a Victorian home. They are painted in that horrible dark stain varnish/shellac type stuff and be damned if I'm gonna spend days sanding them down! Someone says I can make a tank out of heavy duty foundation plastic and use caustic soda. Does anyone have any advice on this, ie. how much I will need, (does it loose it's strength), is it successful, how long should I leave each one soaking etc?

Any help appreciated.

 

[Space cat]

Caustic soda (sodium hydroxide) darkens wood, which might not be what you want. Being water based, it will also raise the surface grain and might cause warping. On top of all that it's not nice stuff to handle; it wouldn't be my first choice.

Shellac dissolves in ethyl alcohol so you could try meths but it's more likely to be oil based varnish. If the meths fails, my next choice would be a bog standard methylene chloride (dichloromethane) based paint stripper. The plastic sheet is a good idea because you can fold it over the top to trap the vapours and stop it drying out.

Methylene chloride works fast; you should see the varnish bubbling up almost immediately. Use a flat scrapper where you can and wire wool dipped in white spirit for the crevices. It's less corrosive to skin than the soda but you'll still want rubber gloves - and goggles wouldn't come amiss either. The vapour isn't nice stuff to inhale so work in a well ventilated area.

 

[Deansplit]

I think I've gone cold on the idea of literally removing them - unsafe for the kids while they're missing plus makes the banister too weak. I've just applied some 'Colron' Hard Varnish Remover (had in the garage for donkey's) which contains the Methylene Chloride you mention - yes it bubbles it up, but when you go to remove the wet residue with wire wool, it clogs and sticks in no time. 80 of these plus the rest of the staircase will take me weeks and I'll probably go insane (if not only from the fumes!) Are you suggesting to make a tank as I originally mentioned, and dip each one? Where would I even get the quantity I need to do that?

 

[Deansplit]

What about coating them as they are with 'Bin primer Zinsser' - then eggshell over that? That's supposed to give it a neutral base so u can paint over with anything?

 

[JohnD]

when you go to remove the wet residue with wire wool, it clogs and sticks in no time.

you did use the metal scraper first, as Space cat advised?

 

[Deansplit]

no - they're round so a bit difficult to scrape off!! However, using a cloth and wiping it off removed more. Will need shed loads of old sheets mind u! What about the BIN primer - any thoughts on that? I couldn't get hold of it recently so I did a test on 5 balustrades using 'International' melamine primer. It kind of slipped on and I went over with 2x top coats, still scratches off if you try tho, just wondered if the BIN one would be any better as it's not water based?

 

[joe-90]

Being as you can remove them - get them dipped professionally. Not expensive - give them the mess.

 

[Space cat]

The secret of painting over old paint/varnish is to get the surface completely clean and slightly rough. I once used something called liquid sander for this. It claimed to remove grease and also 'key' the surface and it certainly worked on old gloss paint. I can't say for sure whether it will work on your varnish - some coatings are notoriously difficult to over-paint - but it might be worth a try. Once the stuff has done its work you finish with standard undercoat and top coat.

Joe-90's idea of letting somebody else have the mess is worth considering but find out how they do it first. Against my better judgement I once sent three 1935 vintage doors, including a glass panelled one, to be "dip'n'stripped". They must've used a water based stripper because it raised the grain into ugly ridges and the nails holding the glazing beads went rusty. To crown it all, the wood was covered in an ugly brown sludge of old paint that had dried on hard!

There was no way they would ever look right varnished. I tried scraping the brown filth off but it was sunk deep into the surface. We repainted two - though several coats later the ridges still show - and scrapped the glazed one.

If you are going to take them out, do it in two stages and remove alternate rails so as to retain some integrity in the banister.

 

[Gees]

See my post below
It takes ages to do but the results are great....

//www.diynot.com/forums/viewtopic.php?p=842397#842397

 

[matz]

the only way to sucessfully strip these things in situ is by using paint stripper. ie Nitromores which is methylene chroride based. However, this stuff is banned in the States and if you have a heart condition the fumes could see you off as they produce carbon monoxide that enters the blood stream

Anyway, what you need to do is make sure you buy the "thick" version of the stripper not the watery thin stuff. Then, you brush it liberally (put as much on at one time that stays on without running everywhere) and leave it. How long you leave it depends on what finish there is on there. If its thick sticky varnish, leave it about a minute max then remove the softened finish with wire wool which must be quite course - about grade 3 (thats grade 3 not grade 000) You'll p[robally need about 6 coats of stripper on each spindle to remove all the finish.

Important points to note

1. Critical how long you leave stripper on, not too long not too short.
2. Important to use correct grade of wire wool. ie coarse or it will clog
3. Be prepared to use many coats of stripper.
4. Have patience

Finally, this material is not user friendly!

It can be a nightmare job...

 

[prospero]

One trick that might work...... Give them a light sanding, nothing too intensive. Just enough to take the gloss off. 120 grit thin sanding pads are ideal for this.
Then paint on french polish (shellac). If you can get the shellac coat to stick, then you have a good surface for water-based paints. Sounds mad, but it works. I am in the picture framing trade and use this method all the time for refinishing on top of existing finishes.
Try a small patch first. When it's dry, try and scratch the paint of with a fingernail. If it doesn't flake off, it's sound.

Edit. Just noticed this topic is a year+ old and not three weeks. It's still a good tip though.