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How to cure a Merbau benchtop?

We used a merbau panel as the benchtop in our recent DIY laundry reno. We attempted to protect it using linseed oil, and then a couple of coats of cabots benchtop clear. However the benchtop is really not water protected. Every single splash from the sink creates a stain in the benchtop, and the worst thing is if we ever put a slightly damp towel/piece of clothing onto the benchtop, the benchtop will leech brown residue onto the fabric which is impossible to clean out of the fabric (I’ve had to throw so many things out). Unsure what’s gone wrong (is it simply the merbau leaching/bleeding colour?) Is there any way we can stop this i.e. put a thick varnish/laquer of some sort over the top of the wood to properly protect it/and the things we put on top of it? Thanks.

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KatieC

Hi @dinaandjake,

Sorry to read that the oil and clear coat have not worked. Our resident DIY expert @EricL will be online later this afternoon to assist, but in the meantime let me tag members @Marty_greenshed, @Brad, and @theDIYedit to see if they have any suggestions. Are you able to post a photo of the current state of the panel? This may assist with finding the best solution.

Katie

theDIYedit

Hi @dinaandjake, sorry to hear that you're having problems with your benchtop. Merbau can be quite tricky as it is well known for extensive leaching. There are a couple of things which spring to mind. With the linseed oil, was it left to completely dry before you applied the sealer? if it wasn't, this can affect to product's ability to seal. Although you can use a water-based sealer over oiled wood, the wood MUST be bone dry because using it. I wonder if this was the issue?

In my experience, it may be better to start again. Are you able to remove the benchtop to sand down and remove the layers of products? This would be the easiest option so you don't have to navigate appliances and sinks etc. With the benchtop clear, this is a food-grade sealer, so if you're not preparing food in the laundry, you could try something a little more robust. I have used Cabot's Cabothane Water-Based Matt Finish before, and it provides a beautiful finish without any sheen. The key is to treat every surface area of the panel, to ensure that moisture cannot enter from any part of the wood, and to make sure it is fully sealed to prevent the tannins leaching.

@EricL will no doubt have some better ideas, but hopefully, you can find a good resolution!

@theDIYedit

EricL

Hello @dinaandjake

It's great that you've received excellent advice from @theDIYedit. Your intention of using linseed oil to protect your benchtop is actually a good idea. However, it takes approximately 10 weeks for the linseed oil to dry off before you can use the benchtop. Mixing an oil-based product such as the linseed oil with a water-based sealer is not a good combination. This now complicates matters as the sealer has essentially trapped the oil from getting out of the timber.

Instead of trying to remedy the coatings that have been put on the timber, I suggest removing the benchtop out of the laundry area and sanding it down again. I understand that it is more work, but it's better to remove all the mixed products on the timber surface and start fresh. Adding more products to the current benchtop surface will complicate matters even more.

Once you've removed all the coatings on the benchtop, I suggest wrapping it in builder's plastic while you decide on the sealer that you want to use. The plastic will protect the benchtop from being exposed to moisture and prevent it from warping.

One way to test and see how a sealer will react to the surface of the benchtop is to test it at the bottom. Turn the benchtop upside down and test a small area to see how light or dark the coating will be. There are products that you can use in tandem, but they often have the same base either oil or water. You'll also see products that say stain and varnish, this saves you from having to buy two products as they have already been combined.

Then you have the sealers, some of them can be used in combination with other products. But they are very specific on which products they can be combined with. My best advice is to use one product only and if you wish to use another product in combination, please make sure that they are fully compatible.

Please note that the remaining Cabots clear has been exposed to the linseed oil, I don't recommend using this leftover product on your benchtop.

Please make sure to wear personal protection such as gloves, goggles and a paint mask while working on your benchtop.

If you have any other questions we can help with, please let us know.

Eric

Jo_Lake

We are having the same way trouble. We used Bondall Monocel Timber benchtop oil. The wood does not seem to be sealed at all. Water marks are left on it and wiping with a sponge makes the sponge dark brown...

Suggestions?

MitchellMc

Welcome to the Bunnings Workshop community @Jo_Lake. It's a pleasure to have you join us and many thanks for your question on preventing Merbau leeching.

In situations where the panel might be exposed to moisture, it's best to strip the tannins out of the timber before installation. Merbau’s superior strength and stability are attributable to its tannin-rich properties. Tannin is a naturally occurring substance in timber that will leach when exposed to moisture. It will stain timber, tiled areas and other surfaces. Objects left on the timber surface will also draw out tannin, creating surface marks.

Are you able to remove the benchtop and use a product like Cabot's New Timber Prep to strip the tannins out of the timber before re-oiling?

Once the tannins have been removed, your benchtop oil will be more readily absorbed into the timber fibres. It sounds like, due to the excess tannins, the timber is not able to uptake enough oil to prevent staining.

Please let me know if you have any questions.

Mitchell

Jo_Lake

Thanks Mitchell,

I'm curious about why this isn't mentioned on the packaging from Bunnings? We wouldn't have bought it if it was going to take so much work to make it usable. The installation and finishing instructions do not state that it needs this extra treatment to remove the tannins? It does refer to leeching tannins the first few times it is exposed to water but doesn't say how to treat that and also states that it can be finished with oil, wax or lacquer? I assumed that finishing it with the oil (which states it creates a waterproof effect) would mean it was in fact waterproof...

Will the Cabot's product you mentioned strip the oil finish out too? Would a hard wax finish be more appropriate? I also don't like how dark the wood has gone with the oil.

MitchellMc

Hi @Jo_Lake,

I apologise that this information is not referenced on the packaging; it's found on the product page under installation. Most of what I've mentioned is purely speculation on why this issue might have occurred. I'll certainly pass your feedback on to the manufacturer to look into.

Oiling timber prevents it from being damaged by water, but it doesn't necessarily stop it from penetrating the timber. This water has penetrated and expelled the tannins creating these staining marks. As noted, the product does reference the tannins leeching when exposed to moisture. You'd need to coat the timber with a water-impermeable varnish to waterproof it. For a kitchen bench, I'd certainly recommend going with a hard varnish coating rather than oil for tannin-rich Merbau.

The Cabots product will do a good job at stripping the oil out of the timber.

Mitchell

Jo_Lake

Thank you! Can you please recommend the best product for sealing effectively?

EricL

Hello @Jo_Lake

If you are looking for a clear finish, I recommend using Cabot's 1L Satin Clear Benchtop Timber Finish. It is a fast drying, heat and stain-resistant varnish. It is safe for use on kitchen timber benchtops. Once fully cured, it is resistant to chemicals, oils and heat from hot cups. It's also available in a gloss finish.

However, if you are after a coloured stain and varnish, there is a wide variety to choose from. My recommendation is to look closely at the label making sure that it is for interior furniture use. I also suggest showing your choice to the senior paint specialist and ask them if it is suitable for benchtops before purchasing your varnish.

Before you commit the entire benchtop, I suggest testing your stain and varnish in a small corner at the bottom of the benchtop. Once it dries off look carefully and see if you like the finish. If you are happy with it, you can now paint the entire benchtop.

If you need further assistance, please let us know.

Eric

Jo_Lake

Fantastic! Thank you!

Jo_Lake

Here's how it turned out ..

EricL

Hello @Jo_Lake

Thank you so much for posting that update on your benchtop. The benchtop finish looks fantastic, did you use the same product for the benchtop on your second picture?

Again, thank you for sharing such a wonderful project.

Eric

Jo_Lake

Hi Eric,

Yes, the same product used throughout. The second picture = the darker colour is due to that portion of benchtop having the oil used on it first (then stripped etc). First pic = only the prep and varnish 👍🏼

gwclarke

Hi @EricL , you seem to be the man in the know and have heard great things!
From what I've read Cabot's New Timber Prep followed by Cabot's 1L Satin Clear Benchtop Timber Finish seems to be the way forward.
This there any curating time post prep to final finish?
My application is a workbench so not so much worried about stains and marks but really wont to eliminate the possibility of marking other timbers that make contact with bench.
If you could confirm process and timeline that would be greatly appreciated. Thanks mate.

EricL

Hello @gwclarke

My apologies for the late reply. After using Cabot's New Timber Prep. My only recommendation is to make sure that the workbench is totally dry. If painted too early the trapped moisture in the benchtop will simply push the clear finish right off the surface.

My best advice is to paint it inside an enclosed space so that dust and debris will not settle on the surface. Make sure to use a superior brush in order to get a great finish.

If you have any other questions we can help with, please let us know.

Eric

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