Oxalic acid - rinse off after?

[Molynoox]

Just applying some 1:6 mix to cedar cladding. Should I rinse it off with water after?
Seems like it could reintroduce the water staining.....

 

[niall Y]

Might be advisable, as it is poisonous. Water staining tends to be where it has affected or penetrated a finish in certain areas. I take it that the finish has been removed prior to treatment, so I can't see that an overall rinse to remove the oxalic acid residue, would cause water staining.

 

[Molynoox]

Cheers
Yeah I stripped it all back.

 

[BucksDad]

Let us know how it went - you are a perfectionist aren’t you

I might do it on my cladding as a lot of it has already been outside and I’m putting on the final pieces this weekend!

 

[Molynoox]

Haha yeah, perfectionism is my downfall
I did the acid a few weeks ago but didn't get chance to re-oil it and it ended up water stained again
I used a slightly neater mix today, applied more of it than last time, properly saturated it, and also scrubbed it with a stiff brush when wet.
Once it dried (very quick in the sun) I noticed some residue which I was able to sand out pretty quickly. I think the residue was a mixture of the acid mix and stuff I'd scrubbed off the surface. I sanded it with 180 grit and it felt really nice afterwards.

The treatments certainly appeared to strip out the water staining, and I've re-oiled it now, which has made it look slightly patchy again. But I think it's better than before and I think it might dry out further over next few days so will see how it goes.

I took a picture after the treatments and sanding but not one after re-oiling. I will grab a picture of it now and throw it up.

Martin

 

[Molynoox]

After acid and sanding

After osmo

Martin

 

[Johnwa]

According to the furniture fixer uppers on you tube you should always wash off the dried residue of oxalic acid before sanding. Apparently the dust isn't good for you. You can of course completely disregard anything shown on you tube.

 

[Molynoox]

Ahaaa I should have known that yesterday strangely enough I didn't think to check YouTube.

 

[mrpercysnodgrass]

Obviously too late late now but oxalic acid should always be well rinsed off. Dry residue/ crystals should definitely not be sanded. The dust is very poisonous. Suggs of madness, his great grandfather who ran a pub down the Kings road accidentally took a swig of oxalic acid which was stored in the same bottles as his medication, he was dead within two hours!!

 

[baldkev]

Obviously too late late now but oxalic acid should always be well rinsed off. Dry residue/ crystals should definitely not be sanded. The dust is very poisonous. Suggs of madness, his great grandfather who ran a pub down the Kings road accidentally took a swig of oxalic acid which was stored in the same bottles as his medication, he was dead within two hours!!

I'll remember that for when i get past it, ive got plenty of oxalic in the shed

 

[XTiffy]

As Oxalic Acid is an acid (clues in the name!), you need to neutralise it. The most redily available alkaline is Baking Powder (Sodium Bicarbonate).

 

[XTiffy]

Just for interest sake Oxalic acid is found in Rhubarb (I never touch the stuff), mainly in the leaves. Though toxic the body obviously can cope with these low levels found in rhubarb.

 

[BucksDad]

As Oxalic Acid is an acid (clues in the name!), you need to neutralise it. The most redily available alkaline is Baking Powder (Sodium Bicarbonate).

Sorry for my ignorance but what do you mean by neutralising it - after treating with the oxalic, wash it off afterwards with a water/bicarbonate mix?

 

[XTiffy]

yes, exactly that. Any acid will continue to react until it is neutralised by the application of a alkali to bring the ph level down. I have used oxalic acid since training in 1977 and we always stopped the action by that means.