- 28 January 2017 at 9:18 pm #308797
I have an old school bench, might be almost 100 years old. It has a place for an ink bottle and previous users created some mess with the ink.
At some places I don’t want to use heavy abrasives, which seems to be the easiest method though. Does anyone have an idea, what type of solvent could work? White spirit doesn’t work, water either, nor does a very aggressive paint remover.
Furthermore, some of the original coating has turned into something brittle, like the surface of a very old rubber ball. What could that be? How to remove that without abrading? Did they have latex paint 100 years ago???
Thanks for any help! I know, I didn’t provide many details, but I told you all I know. If it helps, I will add a few pictures.
Dieter29 January 2017 at 3:23 am #308811Derek LongParticipant
100 years ago they were still making blackboards out of slate. Porcelain “blackboards” weren’t invented until the 1960s.
Denver, Colorado29 January 2017 at 6:39 am #308812Peter GeorgeParticipant
I’d be careful if the surface is painted. The paint would likely be lead based. If it’s a clear coat, i’d suspect shellac. Try denatured alcohol and see if that works.
"New York is big, but this is Biggar"29 January 2017 at 3:40 pm #308814David PerrottParticipant
I’ve used gum turpentine to clean off furniture. A nature soap and water cleans off a lot too.29 January 2017 at 6:28 pm #308815
The bench/desk looks almost exactly like this one:
I cant take a picture from mine, because it is completely disassembled.
See attachment for the original part, I haven’t got a photo from the inside, which is covered with blackboard paint, but it is the same wood of course – all solid, no veneer.
Actually, during a further inspection, I noticed, that the “blackboard layer” is quite thin on some areas. Unfortunately, I don’t know, what caused that, but it must be something, I have at home. So I will keep trying.
The “paint” on the whole desk is definitely based on shellack, except for the desktop, that must have been sanded and lacquered around 1968 (before I got it). By the way, that is the reason, why I wrote the “friendly warning about paint remover”.
In the meantime, I found out, that chalkboard paint is usually based on acrylic or latex paint, with a non-porous filler. I will check, how these can be removed and then get a can of the more suitable one.
But I still hope, that someone can come up with a non-industrial recipe for blackboard paint.
You must be logged in to access attached files.29 January 2017 at 7:54 pm #308820
You can make your own blackboard paint with latex paint and tile grout ( unsanded) in the color of your choice. The grout does set up, so only mix what you will use in about a half hour.
Google “chalk board paint recipe” and several hits come up. It’s best if you let it dry for a few days and then initialize the surface by rubbing chalk all over it and then wiping it off. Powdered chalk or talc will also work. I’ve used rock climber’s manganese block chalk because I had it.
As to removing the ink, clean off what you can with a cabinet scraper, then use oxalic acid, which is what floor finishers use to remove brown and black rust. Paint stores will have it. Old ink was mostly ferric compounds and tannins from oak galls, with perhaps gum Arabic added to seal it. Various acids kept the iron black.
The scraping will help with your gummy finish as well
But the oxalic acid will bleach the wood, so plan on restaining it.
Hope that helps.30 January 2017 at 9:53 pm #308847
Thanks for the info about the ink! and I am not too concerned about the acid, I will have to re-stain a lot on this bench. Would other acid work too?
As for the chalkboard paint, I will see, what kind of paint I can get in small quantities.
Remains the “stuff”. Perhaps, I’ll just take a scraper…
Dieter31 January 2017 at 12:03 am #308850
there are possibly other products, but oxalic acid is what the professionals in the industry. Either it’s the cheapest or the most cost effective…or both.
If you plan on refinishing anyway, try to get most of the ink off first by mechanical means ( a card scraper). The less bleaching you have to do the better. It’s kind of harsh and you will have to sand more if you have to bleach more than once.
I saw you posted about the paint. If you are trying to replicate old blackboard paint for historical purposes or something the binder was probably a casein ( milk) base. But even the companies that make powdered milk paint are using a lot of acrylics in their formulations. And if you use casein you are in experimental mode.
If I were doing it I’d just get a pint of the modern formulation. No one will know and it’s foolproof.
A pint of Rustoleum’s offering is about a tenner USD at the big box store for 30 oz. http://www.homedepot.com/p/Rust-Oleum-Specialty-30-oz-Flat-Black-Chalkboard-Paint-206540/100141287
And Krylon makes a spray on version for about $6 a can, but it is probably not as durable ( a guess)
Put the leftover on a wall or board for the kids. you’ll be a hero.31 January 2017 at 2:27 am #308852
I can get a can at 8 Euro, and it will be enough to make another standalone blackboard and more. I am curious to try the diy-formulas, but if that means, that I have to buy a big bucket of paint, I will just use the commercial stuff.
As for the ink, there is one big blob, more than 1/16″ thick, which is really hard. My scraper didn’t even leave a scratch, and I haven’t found an old chisel yet to do it that way.
PS: I read a bit about oxalic acid, quite interesting stuff. Among other things, it is used as a light bleech (compared to hydrogen peroxide) on wood, especially to remove stains that are the result of metal reacting with tannic acid of the wood. I also found the removal of ink stains mentioned. It also removes rust, but literally, i.e. it turns rust into something else, which is water soluble. Not good to clean tools apparently.31 January 2017 at 8:00 am #308855
Oxalic acid is actually quite effective for derusting tools in some forms and in cleaning products.
There is a powder scrubbing cleanser in the US called Bar Keepers Friend that has oxalic acid as the active ingredient. I use it as the final step after an acid derusting baths to get the grey film off.
It cleans iron and steel, stainless, and is particularly good on chromed objects, nickel plated objects, copper, and brass.
It’s my go-to product for Brass adjusters on planes and for Brass saw nuts, and as the final cleaning on the saw plates. Scrub the plates with crumpled up aluminum foil and the cleanser.
A similar product is called Zud. I think it’s a bit coarser and maybe has more acid. Maybe there is something like it in Euroland.
And some people swear by it for chrome plated things.
- This reply was modified 2 years, 12 months ago by Larry Geib.
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