Triassic Posted February 16, 2019 Posted February 16, 2019 The timber frame is up and the roof is going on. The first roof elements are a couple of oak trusses and oak purlin, these have various black marks on them. Can anyone recommend the best method for cleaning them up?
Jeremy Harris Posted February 16, 2019 Posted February 16, 2019 One way I've seen is to very gently sand blast the oak. Needs doing with care, and tends to be messy, but the results can be very good. I've a feeling the blasting media used isn't actually sand, but something less abrasive. A search on "blast cleaning oak" should find someone close to you that does this, or you can hire the kit and have a go yourself.
Big Neil Posted February 16, 2019 Posted February 16, 2019 Try 'soda blasting'. Just uses bicarb I think
Temp Posted February 16, 2019 Posted February 16, 2019 We have a lot of exterior oak that was similarly marked. Cleaned it up with a MOP fitted with a sanding disc.... https://www.amazon.co.uk/dp/B002QS1LZ2/ref=asc_df_B002QS1LZ258520862/?tag=googshopuk-21&creative=22122&creativeASIN=B002QS1LZ2&linkCode=df0&hvadid=309785472429&hvpos=1o3&hvnetw=g&hvrand=14935090843020364098&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9044886&hvtargid=pla-561971005126
Triassic Posted February 16, 2019 Author Posted February 16, 2019 Our beams have the rough saw marks on them, which we’d like to keep. I was thinking more along the lines of spray on type cleaning products, that would remove the black marks, without having to remove the wood.
Jeremy Harris Posted February 16, 2019 Posted February 16, 2019 The black marks are actually in the top surface of the wood, they are a chemical reaction between the tannins in the oak and usually something like steel that's been in contact with it, so I don't think you can wash them out.
newhome Posted February 16, 2019 Posted February 16, 2019 Not sure if this helps? http://www.woodworkersuk.co.uk/blog/tips-and-tricks/my-oak-has-gone-black/
Triassic Posted February 16, 2019 Author Posted February 16, 2019 (edited) According to the article Oxalic Acid is the stuff I need to clean the black marks. Apparently these are caused by contact with ferrous metal, fork truck forks, tools, metal banding etc. Now where to buy Oxalic Acid? Edited February 16, 2019 by Triassic Typo
PeterW Posted February 16, 2019 Posted February 16, 2019 3 minutes ago, Triassic said: According to the article Oxalic Acid is the stuff I need to clean the black marks. Apparently these are caused by contact with ferrous metal, fork truck forks, tools, metal banding etc. Now where to buy Oxalic Acid? Thornes sell small amounts. I’ve bought from them before. https://www.thorne.co.uk/index.php?route=product/product&product_id=7434&gclid=CjwKCAiAhp_jBRAxEiwAXbniXc3zm9-UWhJQDzVfbd61UnUI_AyyV6EydWI_IQ2Rq4fEWKnVhRAGKBoCOV0QAvD_BwE
Triassic Posted February 16, 2019 Author Posted February 16, 2019 Having never used the stuff before, am I buying 100g or 1kg?
PeterW Posted February 16, 2019 Posted February 16, 2019 You don’t need a lot but beware that you could bleach the oak slightly so may have to do the whole truss ..!
Jeremy Harris Posted February 16, 2019 Posted February 16, 2019 I'll also add that I've tried using oxalic acid to get rid of black marks on iroko decking (much like oak as far as staining goes). It was a bit hit and miss, and definitely lightened the wood a fair bit, and not all the black marks came out. I ended up sanding the deck back and painting it with Deks Olje, which wasn't really the look I wanted.
Triassic Posted August 15, 2019 Author Posted August 15, 2019 I still haven’t got round to cleaning the oak beams yet ! Not enough hours in the day ! I want wondering about soda blasting, has anyone done any DIY soda blasting and did it clean the marks off the oak?
Triassic Posted April 7, 2020 Author Posted April 7, 2020 Is we’re in lock down, just started our 5th week I finally found time to start cleaning the oak beams. Wow! Oxalic acid works wonders, if been sceptical given how many black marks and stains we had. The Oxalic acid cleaned up the lot. All I need to do now is treat the cleaned up oak and then over it all up ready for plastering. Mind you the plasterboard supplier is shut and the plastering team in lockdown. 1
JFDIY Posted April 7, 2020 Posted April 7, 2020 It was suggested to me to clean the oak after plastering to help get rid of any plaster dust etc. If already clean I'd mask them well, wet plaster seems to leave a chemical burn onto oak which is very hard to get out.
Triassic Posted April 7, 2020 Author Posted April 7, 2020 5 hours ago, JFDIY said: It was suggested to me to clean the oak after plastering to help get rid of any plaster dust etc. If already clean I'd mask them well, wet plaster seems to leave a chemical burn onto oak which is very hard to get out. We’re going to treat them with Danish oil or similar, then wrap them in bubble wrap, we have loads of the stuff, everything comes in bubble wrap!
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