Another outdoor-timber-protection thread

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neb

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#306500 28-Jul-2023 19:55

This one's a bit different because not only do I have to protect the timber I need to change its colour, but without just slathering paint on it. The background is new pine additions to an existing composite deck that looks like this:

The obvious solution is stain and varnish, but every existing thing has stain not compatible with overcoats, or any colour you like as long as it's kwila, or alkyd-based or waterborne so it disintegrates after two years or similar (max. lifetime 2-3 years seems to be a common refrain with these products). Does anyone know of anything that has a good colour range including the one above and a compatible varnish I can put over the top to protect it? In brief oil-based stain in the above colour compatible with oil-based varnish to coat it.

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#3109424 28-Jul-2023 21:03

Have a look at the Sikkens Cetol line of products: https://www.sikkens.co.nz/products/.

I did some outdoor furniture 3 years ago with HLSe and still looking mint despite taking a pounding in a coastal area. Bunnings stocks it, it's one of their spendier options.

That said, this isn't exactly what you asked for, since it doesn't have a varnish overcoat. I'm no fan of varnish outside because it will yellow in the UV (I know there are marine grade options that deal with this better). You also need to be careful with anything glossy underfoot outside in the wet.

But ultimately anything at all clear is going to break down a lot faster in NZ UV than the paint equivalent.

Edit: phrasing

neb

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#3109432 28-Jul-2023 21:22

mdf: Have a look at the Sikkens Cetol line of products: https://www.sikkens.co.nz/products/.

That's the alkyd-based one, quoted life span of 2-3 years, and those are the products not already specifically noted as being for south and east-facing areas only.

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#3109457 29-Jul-2023 07:48

neb: This one's a bit different because not only do I have to protect the timber I need to change its colour, but without just slathering paint on it. The background is new pine additions to an existing composite deck that looks like this:

The difficulty with colouring the pine to match the composite could be that if the composite is like a friend's Ecologix it will be changing. New Greystone planks are dark almost black whereas older planks have faded to a mid grey. Will your stain change at the same rate?

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#3109687 29-Jul-2023 22:18

Bung: The difficulty with colouring the pine to match the composite could be that if the composite is like a friend's Ecologix it will be changing. New Greystone planks are dark almost black whereas older planks have faded to a mid grey. Will your stain change at the same rate?

Yeah, that's been a consideration here, will they fade in sync? The decking, Outdure ResortDeck, hasn't really faded much so far so I'm planning to get something a bit darker than its current colour and assume it'll fade a bit to match the deck. Also it doesn't need to be an exact match, just close enough is fine (tested this with a few stained wood samples).

After a visit to Bunnings it looks like I'll go for Bondall Monocel, they have the shade I want even though it's not on the Bunnings web site and the instructions, also not on the web site, say you can stop coating as soon as you reach the shade you want as long as you overcoat with Monocel clear varnish, which I was planning to do anyway.

So as long as the test pieces work out it'll be 1-2 coats of solventborne stain+varnish overcoated with 2 coats of solventborne varnish, which is probably about as good as you can get.

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#3112544 7-Aug-2023 03:09

And the Monocel won't work because their Merbau, which is the matching colour, isn't actually Merbau but Chestnut. In other words if you buy the Chestnut stain and varnish you get Chestnut, and if you buy the Merbau stain and varnish you also get Chestnut. The paint folks at M10 couldn't explain it, and said they'd call Bondall on Monday for an explanation. They were actually quite helpful and opened two different sized tins on the assumption they'd be from a different batch, and both were the wrong colour.

So of the various options there are:

Bondall: Their claimed correct colour is actually a completely different colour.

BP: Interior use only.

Cabots: Water-based, and Cabots make rubbish products in general so I tend to avoid them.

Feast Watson: Their Merbau might be OK, still investigating.

Minwax Polyshades: Indoor use only.

Procoat: Limited colour range, no good match.

Resene: Best colour range but can't be overcoated to protect it and therefore needs recoating every 2-3 years.

Sikkens: Alkyd resin with poor UV resistance.

Wattyl: Very limited colour range, no good match.

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#3112595 7-Aug-2023 08:41

neb: Resene: Best colour range but can't be overcoated to protect it and therefore needs recoating every 2-3 years.

Is that can't be overcoated or Resene don't make the required overcoat?

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#3112743 7-Aug-2023 11:47

Bung: Is that can't be overcoated or Resene don't make the required overcoat?

Can't be overcoated:

Resene exterior stains ( called Woodsman) cannot be overcoated with any oils or varnish. Woodsman is a fully penetrating stain that is designed to erode over time for easy maintenance. We regard stains as a high maintenance coating needing an additional coat every 2 Summers.

Just got a reply from Aalto / Procoat to say the same thing, can't be overcoated.

Argh, this is ridiculous! How are you supposed to protect an exterior handrail when the colour doesn't match one of the only two or three shades of stain+varnish that are available?

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#3112820 7-Aug-2023 12:54

neb: Argh, this is ridiculous! How are you supposed to protect an exterior handrail when the colour doesn't match one of the only two or three shades of stain+varnish that are available?

Wait, what are you doing? I thought this was a pine deck?

If it is just the handrail (i.e., not being walked on), you can use Resene Colorwood + Altex Marine Varnish (see pp 17-18 re: doors and joinery; timberlock also recommended). Colorwood you can mix, match, lighten and darken to your heart's content. Usual disclaimers about UV exposure apply though.

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#3112824 7-Aug-2023 13:11

The existing deck is composite, the handrails being added are pine that I need to have match the deck, see the OP.

Isn't Colorwood water-based, meaning you can't put an oil-based finish over it? And AFAIK it's interior only, the Woodsman that can't be overcoated is exterior.

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#3112827 7-Aug-2023 13:17

Yes, typically. But as ever exceptions apply. Look at the pages linked in the previous post.

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#3112828 7-Aug-2023 13:21

Yeah, been reading them, but I've become wary of over-interpreting what's said in different parts of vendor documents in terms of mixing and matching different finishes, one section says A and another says B. It certainly looks like you can put oilbourne over waterbourne and use it externally, but I'll give them a call to confirm.

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#3112829 7-Aug-2023 13:25

FWIW, I think Altex is a "varnish" rather than a varnish. Polyester based from a very quick google, but treat that with a grain of salt.

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#3112835 7-Aug-2023 13:43

The Resene doc says to use Resene Qristal [*] Clear polyurethane so it looks like you can put standard polyurethane over it. The Altex MSDS says it's an alkyd varnish and that stuff isn't known for its UV endurance, but it also claims "the longest lasting finish of all competitive single pack varnishes tested" (backed by no evidence whatsoever) so they seem confident it'll last. But then elsewhere it says "we do not recommend it for weatherboards or surfaces with a high exposure to U.V., such as North facing windows and doors" and "will need regular recoating", so maybe "competitive single pack varnishes" means "other alkyd-based varnishes" rather than "any kind of varnish including non-alkyd ones".

This is why I made the comment about over-interpreting what's in some of these docs, I don't think they've been extensively cross-checked for consistency.

[*] Sounds like a millennial girl's name, "our eldest is called Qristal and her sister is Ashleigh".

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#3112855 7-Aug-2023 14:34

Just talked to a very helpful person at Resene and they said that with our UV levels it's more or less impossible to do, you're going to get degradation over time and the reason why the stains are designed to erode as they're damaged by UV is to allow recoating later, so it sounds like a sacrificial ablative coating. With a varnish it'll need stripping in order to recoat, so initially it'll be fine and then when it's time to recoat it's a massive headache to strip back.

The Colorwood + varnish combo is recommended for sheltered areas like front doors but not for anything with lots of sun exposure, if you wanted to try it you could do it with five to seven coats of marine varnish, but then stripping it will be even more problematic.

Another interesting point made, which I'd already encountered with the Sikkens, was that products advertised for outdoor use overseas just don't work in NZ with our UV levels, they break down far too quickly.

"Made a note in my diary on the way here. Simply says, 'bugger'".

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#3112860 7-Aug-2023 15:06

Maybe instead of (poor) colour matching go a deliberately different colour as a 'feature'

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