We are 95% sure its Kwila, its not had an oiling in a VERY long time, its about 12 years old. The wood is hard and nails dont seem to pop up which is a plus.

We have tried 3 brand name deck cleaners and none of them have removed the silvering, its clean, but it has patchy silvering.

Is the only fix to the problem to sand before oiling? If so is a stand up belt style floor sander the best to hire and use?

Its about 60sqm all up.

 

Have you tried a deck brightener?

 

What kind of product is that, could you link to a brand for me? Not something we come across but might be called something else here. The Cabbots is meant to remove everything back to the bare wood, not even close haha.

 

I would try teak products (cleaner & brightener) on a small area to see if you like the affect.

 

There are different brands, I usually clean PT pine decks with bleach which negates the need for a brightener. Here is one - https://www.diyhomecenter.com/deckwi...iABEgJ8sfD_BwE

 

Thanks guys, Ive tried cleaners with bleach as part of the ingredients.

Cabbots have the range from cleaning to oiling, but they dont tell you what to do if the silvering/grey wont come off.

I contacted a deck guy to sand it and he said "no no, you clean the deck", ugggh. For 50sqmd wanted $3k. No thanks lol, worst case a deck sander is $75 for 24 hours.

He wouldnt tell me whats in their cleaner or give me any tips, oh well fair enough, but he said they use a pressure washer and when I mentioned mine and which attachment to use he said oh no no these are different to household ones.

I came across a commercial deck cleaner site and what they use depending on the problem, was quite a number of different chemicals.

From what Ive seen by the website that shows how to do it, its a low pressure "FAN" type washer. First apply the cleaner (we will have to try a more caustic one) and after time they use the fan pressure cleaner, then they apply a brightning agent, and optional sand, this is where Im thinking easier just to sand the silver off in the first place and get an even look. hmmmmmm.

 

Try a section with bleach. The good bleach should be mixed 50/50 water, the bargain bleach is already diluted. Apply the bleach and let it set but don't let it dry before you rinse it off. That has worked well for me over the yrs although I've never run across a deck built with kwila.

 

I tried the bleach to no avail :-(

 

So we tried all the expensive pre mix cleaners and even brightners, waste of money.

I had read about Oxalic acid prior (be sure to wear safety gear including a proper adequate respirator, refer to link below and other safety information on the internet). So we bought some from the hardware store. It says 1:10 dilution ratio, but we know from other "Timber" anti weathering cleaners etc it was unlikely to work, so we went 3:10. And bingo, its nearly back to the non silvered hard wood. Id say one more round and it will be done. We tried it out on our timber and no issue, back to looking like timber that has been used.

Im starting to wonder if this is Kwila or another type of hardwood. Either way it keeps its UV/Weathering silvering very well and many people like that look. I will have a look in my house project management notes to see what they built it with.

Just a note on this acid, be very careful and always wear a proper respirator, it may cause lung bleeding as per below link;

• Oxalic acid will remove water and rust stains, plus teak stain, and can be used to lighten the graying effect of weather-exposed wood. Note: Some restorers consider oxalic acid highly toxic, since the crystal form it typically comes in can be inhaled and cause lung bleeding. Many recommend using the A/B bleach for safer practices and greater overall bleaching power.