Decking oils - which is best?

[ProjectPete]

With a lot of talk about decking ('tis the season after all) I thought it'd be good to share our experiences and preferences with decking oils as there are many on the market. There's water based and oil based. Different levels of gloss. Colours. And everything in between.

For me, you can't go past Cutek Extreme. It's a top quality product and one I've used several times myself. I know some carpenters and a couple of building supplies companies that use/recommend it too. It gives a beautifully natural finish (without tinting), is long lasting and has the versatility of being tinted to your desired colour/tone. I've always found the timber I've applied it to is well preserved over the years. (I don't benefit from the "promotion" of this product)

Unfortunately it's not available at Bunnings, but I have always heard good things about Cabot's and Feast & Watson (which are available at Bunnings) too.

Keen to hear from others.

PS WÜRTH SS decking screws FTW.

[Em24]

Hi Gents,

I have installed timber windows at the front 2 years ago and treated them with several coats of Cutek Extreme CD50, bought as per recommendation from a "timber expert" as I wanted to keep the natural look of the timber. I reapplied it every 6-7 months and followed the instructions to the dot.

Unfortunately with all the rain last year, I had mould at the sills and also saw that the timber had cracked on several places. Now I am trying to put on the Cobat's Exterior (oil based) stain as per the window manufacturers original suggestion. I wish I had not listened to him in the first place.  😓Picture below shows after I treated the mould.

[EricL]

Hi @Em24 

Welcome to the Bunnings Workshop community. It's wonderful to have you join us.

In order to give you a comprehensive recommendation, can you please tell us what you treated the mould with? It looks like you sanded the surface, and it seems like the mould is still there. Looking at the bottom of your window it looks like the sealer has degraded very badly. If you are planning on putting on a new stain and varnish on your window frame, I suggest sanding the frame back to timber so that any new sealer or stain you apply will be properly absorbed by the timber.

Painting directly over old stains and sealers is not advisable as the wood will not be able to absorb the new seal and will simply sit on top of the old sealer. In order to help you with sanding the window frame, I suggest investing in an Electric Detail Sander. This will greatly reduce the amount of time you'll be spending sanding down the window frames.   

Since you already have the Cabot's Exterior stain, I suggest testing it on a small portion of the window frame where you've already sanded. Let the stain settle and see if you like the finish. If it's satisfactory then you can commit the rest of the window frames.

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

Eric

[Em24]

Hi Eric,

As said, the original stain is Cutek Extreme CD50, which is oil based stain absorbed in. I never had a sealer. When I discovered the mould, I sanded it back of course, treated it twice with a vinegar solution. Not really trusting this, I then used, Mould action spray, Feast Watson Woodclean and UltraPrep Mould Killer from Intergrain, just to be sure. I can't remember at what stage I took the pictures attached, but the kind of black stains never went away. I then recoated it with Cutek Extreme CD50 again (twice) to protect it. 

But as said, I am still not sure whether this is protection enough to avoid anymore damage. It looks bad as it is, see current photos. I am thinking I should go with the Cabot's exterior stain, but am not sure if it needs sanding or can I just put it on as both are oil based stains. I should not have used Cutek in the first place. Or shall I go with a varnish altogether?

[EricL]

Hi @Em24 

If part of the timber still has the old oil stain attached to it, it will cause uneven absorption of the new oil stain. This is one reason for the light and dark stain on the timber surface.

I don't recommend painting over it the way it is as it will not protect your window frame properly. 

I understand that it will be a bit of an effort, but I still recommend sanding the timber frame and removing all the old stain on it. I propose sanding the bottom portion of one of your window frames. Preferably one that has not been repainted, it will take you a bit of time, but it is possible to sand away the old stain.

Once you've cleared the area and it's free of the old stain, you can now test the Cabots stain on the freshly sanded surface. You should in theory have a uniform finish on the surface with no light or dark spots.

I also suggest having a look at these discussions - How to vanish and stain timber window and door trims? by @charliebohl and What do I use to stain new window trims? by @Woody1.  

If you need further assistance, please let us know.

Eric

[Em24]

Hi Eric,

The dark stains on the sill are from the mould, that never went away with the mould treatments. It is definitely not a old stain. I could not get rid of the darkening from the mould after using several types of mould killer and wood cleaner. When you say "repainted" I only used stain, not any sealer, just for clarification. Do you recommend staining or vanishing the timber frames. Which one is better in the long run. 

Thanks

Em

[EricL]

Hi @Em24 

Using varnish on window or door frames often lasts longer than stains. If you decide to use varnish over the stain, please make sure that it has fully cured and that the varnish you use is compatible with the stain you applied to the window frame. I recommend speaking to the paint specialist at the store on your next visit and asking them about varnish compatibility.

If you need further assistance, please let me know.

Eric