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Exterior woodwork change from dark to light

Hi Everyone,

Newbie question: I am planning on tackling our black facias and eaves over the coming months, and although the look to be in reasonably good condition, I want to change the colour from black to white, I have read Russ’s post ‘Best oil-based gloss paint for exterior woodwork on period property’, (many thanks!) and am planning to use the Zinnser Coverstain and Sikkens Rubbol AZ - will the Coverstain be enough to block out the black colour, or am I in for some heavy sanding?



Hi Wendy

Zinsser Cover Stain is a great choice of primer/undercoat for Sikkens AZ, it is much better than the dedicated Sikkens Onol Undercoat.

However, if you are changing from black to white you will find one primer and one topcoat won’t offer sufficient opacity. You will definitly need two topcoats, maybe three. If you applied two coats of Cover Stain and one coat of AZ this might work but you would need to try a section first. I wouldn’t try sanding the black colour off if it is adhering well. There is no need, and you will just create more work for yourself.

If you haven’t used either product before I would get a litre of Owatrol Oil to condition the paint. It will help both products flow easier.

A word of warning about Sikkens AZ, it is not an easy product to apply. It doesn’t brush onto the surface well and has a tendancy to build up and run. It can also take an age to dry.

Have you thought about using a water based product instead? Sadolin Superdec Gloss won’t give you the very high shine of the AZ, but would apply in half the time and give good results. Apply this product over the Cover Stain as you would the AZ. This paint will require two topcoats for maximum sheen level. To condition this product I would go for XIM Latex X-Tender available from Decorating Direct.

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Hi Ron,

I really appreciate you taking the time to post a reply. I will certainly check out the Sandolin product and conditioner. As long as it protects and stays for a reasonable number of years I am not particular! Thrilled to be avoiding sanding too, fabulous!

Whilst we are at it, any fillers/hardeners you can particularly recommend - after dealing with the eaves and soffits, I will be moving on to my windows and cills, the latter of which, sadly will require intervention of the filler kind…



Hi Wendy

If you are looking for a product that will last and not fussy about shine, also consider Mythic Exterior Semi-Gloss. This product will give you the protection you require at a reduced sheen over the Sadolin Superdec. It will also apply and cover better to.

Regarding fillers it depends what you are doing. For cracks and very small holes I just use caulk. Make sure it can be used outside though. Also a lightweight filler would be fine for small and medium holes. Polyfilla OneFill is a great product. I avoid two-pack and cellulose fillers as they are harder to sand. But if you are building up corners these products are stronger in that application.

Prepare the surface first and apply the Cover Stain. Then do your caulking and filling. Put the filler in slightly proud then sand smooth when dry. You will need to prime the filler, no need to do the caulk, before finishing. Cover Stain is fine for this job.

If you go with a water based finish you must use a synthetic bristle brush for the best finish. For the Superdec go for a Proform Picasso or Wooster Chinex FTP. The Mythic will require a softer filament such as a Corona Tynex/Orel. All of these brushes are available in flat and angled designs.

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re fillers, if there’s rot and decay then its really worth looking at the ‘Repair Care’ resins. They can save a number of serious rot situations at a fraction of the cost of carpenter/splicing/replacing etc. While it seems like a simple two part resin (two cartridges) it takes a certain technique to apply so its worth going on the one day course (cost of two cartridges!)to ensure you get the long term benefit.
Its a superb product,ideal for repairs to mouldings and external corners etc as it shapes so easily, doesn’t slump nor go brittle like trad two part body filler type fillers.

Also would highly recommend the Toupret Fine Surface Filler (blue tub)for the important final finish on doors and cills
Dave d9 decor Bristol