Oxalic acid for cleaning teak

Some questions fron a newbie to teak deaks

what sort of concentration of oxalic acid should one use if one just wants to brighten up teak and rid it of mould stains rather than a full bleach.

how long do you leave it on

is just rinsing off OK or should yuou use borax


Tanks in adveance
 
my Woodworkers Pocket Book (ISBN 0 237 35195 1 ) says 1oz oxalic acid in 1/2 pint hot water.

Also says wipe over with borax, about 1/2 oz to 1/2 gallon, wash with clean water and dry.
 
VicS beat me to it. I would have said 2oz to a pint to start with but you could always increase the strength if what you are cleaning seems to demand it. Borax may be a good idea but I never used it. Just gallons and gallons of clean water (don't forget to hose down the run-off too)
 
gjgm said:
I also use the Wessex gear; there is certainly a difference between the two bottles, which is why I was wondering how come OA on its own is sufficient?
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Again I've used both in the last week or so, OA cleans the teak but the Wessex 2 part stuff leaves it looking a lovely golden colour. I now intend to first clean with OA and then use the Wessex potions.
 
I used the Wessex products for the first time at the weekend after using many other Teak Cleaners over the years; I was very impressed.

There is though some very clever marketing that has gone into this products as part one when part two is put on (after rinsing) lightens immediately - reminds me of school Chemistry.....

Very impressed with the product though.
 
davidej said:
These two bits of advice conflict quite drastically:

2oz per pint is a pound a gallon

half oz per half gallon is of course an oz per gallon


weaker by a factor of 16!
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One is the suggested concentration of oxalic acid the other is the suggested concentration of the borax.

The concentartion of boarx is very small compared with the concentation of the oxalic acid when you convert to molar concentartions .. the only way you can meaningfully compare them.

Borax is the decahydrate of disodium tetraborate so it is Na2B4O7.10H2O which gives an RMM of 382.

Oxalic acid may be anhydrous, C2O4H2 or the dihydrate, C2O4H2.2H2O
RMMs 90 and 126 respectively.

So even if the oxalic acid used is the dihydrate the molar concentrations differ by a factor 48.5 not 16!

As to whether one is stronger or weaker than the other I don't know. One is a weak acid, the other a weak base but I don't have ionization constants to hand to compare.
 
davidej said:
These two bits of advice conflict quite drastically:

2oz per pint is a pound a gallon

half oz per half gallon is of course an oz per gallon


weaker by a factor of 16!
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Do they really?? VicS said
my Woodworkers Pocket Book (ISBN 0 237 35195 1 ) says 1oz oxalic acid in 1/2 pint hot water.
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whereas I said
I would have said 2oz to a pint to start with
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. Has my arithmetic and aged brain let me down that badly?:rolleyes:
 
longjohnsilver said:
Again I've used both in the last week or so, OA cleans the teak but the Wessex 2 part stuff leaves it looking a lovely golden colour. I now intend to first clean with OA and then use the Wessex potions.
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I think you might be wasting time & money if you do: Part 1 of the Wessex product is a proper cleaning agent (saponifier) and Part 2 is Oxalic acid (AFAIK)
 
rudolph_hart said:
I think you might be wasting time & money if you do: Part 1 of the Wessex product is a proper cleaning agent (saponifier) and Part 2 is Oxalic acid (AFAIK)
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Quite happy to carry on using both, I have 3 separate areas cleaned by either just OA or Wessex and another done with both and by far the best is a combination of the two. I bought a large tub of OA for about £20 which will last years so very little money spent and not wasted.
 
I'm pretty sure (haven't done a chemical analysis) that part 1 of the Wessex cleaners and equivalents is sodium hydroxide solution. Part 2 is oxalic acid. Appropriate PPE recommended for both. I have had very good results with these 2 part systems.
 
I have acres of teak deck and now swear by wessex, its very good stuff. My decks look great all year, just a wash down with salt water occasionally.
 
Less common now as it is difficult to buy, and is mainly used for prevention of mould growth than cleaning. Patio Magic is a good alternative for this purpose. Most of the teak cleaners such as the Wessex brand mentioned by many are oxalid acid based for the cleaning part and then a second part which brings out the original teak colour.
 
pheran said:
The 'no brushes', 'no pressure washers' advice is good whichever cleaner you choose. This is because teak is mistakenly regarded by many people as a hardwood - it isn't. Its a natural hybrid with the 'hard' bits existing a 'pips' surrounded by much softer wood. Hard brushing or pressure-washing tends to wash out the 'pips' leaving you with accelerated wear and deterioration and, eventually, an expensive bill for replacement. 'Sponge only' is good practice but even there, you still have the argument of only across the grain or with it!!
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Good points. I power washed part of mine last year and it ruined it. when it dried it got ridges thru it. thought is was due to the heat but it ruined it. Just a small area though , but be warned.
Steveeasy
 
gjgm said:
Why do some cleaning packs have two treatments?
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It's easier to justify the price being charged. Half a lifetime's supply of OA will cost you less than one bottle of the GRP/teak/aluminium wheel cleaners for which it's the active ingredient; if you really feel the need for full effect of the 'real' stuff then add a single drop of the blue/red/green food colouring necessary to match it
 
Keith 66 said:
No need for expensive unguents they are all snake oil. Seawater & scrub with soft brush or scotchbrite pad. Thats it maybe twice a season. Teak goes silvery grey & looks good.
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That maybe OK if the boat is at sea or kept in an area where there is minimal atmospheric pollution but many boats are kept in marinas in industrial areas and the biggest problem is dirt from fallout plus mould from being in a damp atmosphere - often worse on the side of the boat facing away from the sun. You only have to see the dirt run off when you do use a cleaner to appreciate now much dirt is embedded in the wood, particularly with today's plantation teak that is used for the thin veneers in most modern boats.
 
Keith 66 said:
No need for expensive unguents they are all snake oil. Seawater & scrub with soft brush or scotchbrite pad. Thats it maybe twice a season. Teak goes silvery grey & looks good.
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That silvery look is the wood breaking down. In a few years so.much is lost that replacement will be necessary. My toe and hand rails are now so thin that the teak plugs over the screws have popped out. Fortunately Woodskin has saved what is left.
 
Eek, you've got me worried now Vyv! I don't suppose you have any photies of how woodskin looks when applied to teak? is it good for a cockpit, or is it slippery?
 
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