Merbau Tannin & Limestone

Greetings,

I am currently building a merbau deck which is surrounded by a recently laid reconstituted limestone garden wall and I have two questions:

1. Tannins - does anyone have any experience with the tannins in the merbau leaching on to limestone and in particular does anyone have any good remedies for removing / cleaning? I am considering using bleach and/or a high pressure hose. (the tannins haven't leached yet but I suspect this will be unavoidable after the deck gets wet).

2. Finishing - after reading through posts on this subject I plan to leave the deck untreated for a month or so and then clean and finish with Spa & Deck. Is this a bad idea or am I on the right track? It seems logical to me to let some of the tannins come out of the timber initially before trying to finish off with decking oil.

Excellent website, great for a young guy like me who is "learning the ropes".

Any ideas?

What might be a solution is to try and prevent the tanins from staining the limestone in the first place. I gather that the timber is above or near the limestone and as this stone is very porous it could turn out to be a royal pain in the a@# if it gets stained. I am faced with this often when I am coating decking and believe me you do not want any coating landing on this stone. Spa&Deck is next to impossible to get out of porous stone. If it was my deck I would look at heavy builders plastic or light weight blue tarping or a combination of both. I use both when I am coating a deck which is above a lower level of exposed aggregate and plain concrete,brick pavers and white paint sucking limestone pool pavers. I have found that 8-10 litre plastic buckets full of water are the best for holding down the tarps and keeping it from lifting in the wind. You can never have enough buckets. Buy the 79 cent ones from the cheap stores. To save a lot of grief I would just build the deck and before you put any new timber above the limestone tarp it, As soon as it is built scrub the timber and rinse 2-3 times with either Flood powerlift or napisan and then get it coated ASAP. When you are using Spa&Deck stain hose on water all over the tarps so when the stain lands on the water it will be a little diluted by the water


Good luck

jimj www.restore-a-deck.com.au

Thankyou for the good advice Jim.

I have been following your posts with keen interest as you appear to be the "go to man" on deck finishing.

I guess it is the old adage "prevention is better than the cure".

I second the clean it straight away method... Spa n deck is a bugger to get off stone as i found out the other week when i found 4 tiny drops on the customers white stone and i had tarped the job beyond stupid...
Domestos has gotton the stain off before for me in pools where its been impossible to cover..
The best method is to prevent staining in the first place so clean a coat asap

cheers utemad

Another commercial product distributed by Flood into Australia is a series of cleaners called Motesnbockers "Lift Off" stain Removers. There are 5 different ones and numbered 1-5. Each one works to clean certain things. The number 5 is an acyrlic paint stain remover. I find it works pretty well on dried Spa&Deck but in all honesty it is better to just not get it on porous material and I alwayshave 2 wet rags in my pockets so if I accidentally touch something like the side of a house I can get if off straight away while the paint is still wet. This product is sold where I live at Bunnings in the cleaning products division for around $22.00.

Thanks

JimJ www.restore-a-deck.com.au

Thankyou both for the advice.

In retrospect I should have created a different design.

I am going to seal the limestone wall with "topseal" or similar and then follow your advice above.

Ok your best bet is putting a sealer on the stone prior to building the deck.

Choosing a sealer that will repel moisture and tannin ingress will be the issue.

You may have to put a couple of coats of stone sealer on to get the desired repellant of water laden with tannin.

If you have already tannin stains which may happen on raw sand face render (creme/white) or limestone or creme brickwork you can use a bleach to bleach the tannin on the stone.

"Always" do a test patch in an unseen area to see if you will get the desired result.

You don't actually remove the stain, you are lightening the stain.

Hydrochloric acid melts limestone (it reacts with lime in mortar to remove from brick) so don't do what others do and reach for the hydrochloric acid every time you have a stain or issue with these things. eg: Efflorescence