Knots?
- Thread starter seanoge
- Start date
Sponsored Links
When you say a while back, you mean years?
Looks to me like the knots have dried out. How long after painting did the paint peel?
Looks to me like the knots have dried out. How long after painting did the paint peel?
Sponsored Links
Ok, so rubbed down & 2 coats of Alu. primer. Was planning to use Cuprinol Ducksback. I have used it elsewhere in the Garden, and it's excellent far better than Ronseal.
Any thoughts as it says " Ducksback is not deep penetrating but very much relies on the timber texture for adhesion. For this reason it is recommended for rough sawn timber only. If the construction contains smooth timber components, or has lost texture through weathering then adhesion performance will be reduced. The product only becomes water repellent when it is fully dry and until then it can be damaged by heavy rain. In addition, surface dirt, algal growth and any previous treatment which retains water repellency may repel the Ducksback, causing poor adhesion".
Any thoughts as it says " Ducksback is not deep penetrating but very much relies on the timber texture for adhesion. For this reason it is recommended for rough sawn timber only. If the construction contains smooth timber components, or has lost texture through weathering then adhesion performance will be reduced. The product only becomes water repellent when it is fully dry and until then it can be damaged by heavy rain. In addition, surface dirt, algal growth and any previous treatment which retains water repellency may repel the Ducksback, causing poor adhesion".
Surely you don't use Ducksback over the old grey paint and aluminium primer anyway???
I take it you only applied the aluminium primer over the knots?
If you want an opaque colour finish, you could try Sadolin Superdec.
You will need to sand the surface first to get a 'key'.
You will need to give the aluminium a light sand, without damaging the surface, to ensure the Sadolin sticks.
You should get three coats on on a warm day.
I take it you only applied the aluminium primer over the knots?
If you want an opaque colour finish, you could try Sadolin Superdec.
You will need to sand the surface first to get a 'key'.
You will need to give the aluminium a light sand, without damaging the surface, to ensure the Sadolin sticks.
You should get three coats on on a warm day.
It may be an idea to use an oil-based undercoat on top of all that aluminium primer, then use the Sadolin Superdec after that, and in years to come.
10 year oil based primer and 10 year oil based gloss. All the cracks and holes should be filled. All the algae and mould should be killed (I use thick bathroom bleach). The knots look spent and have no sap left in them and shouldn't affect the paint once the cracks are filled.
If you are tempted to fill cracks using paint, it will looks good at the beginning, then fails. Cracks and holes are usually filled using 2 part wood filler. For non-load bearing surface, use of hybrid polymer sealant is also possible. I am testing the hybrid sealant, but don't have long term results. I know they are good, at the least, for a couple of years unprotected by paint.
Last edited:
What kills paint:
1. water getting to the substrate
2. Mould/algae living under it
3. Expansion and flexing of the substrate. Good quality paint is flexy and stretchy
4. Low quality paint that will expire itself just from time under sun/ultra-violet. Wide spread cracks then appear. Good quality paint also crack but only in stress areas or in areas not properly done.
1. water getting to the substrate
2. Mould/algae living under it
3. Expansion and flexing of the substrate. Good quality paint is flexy and stretchy
4. Low quality paint that will expire itself just from time under sun/ultra-violet. Wide spread cracks then appear. Good quality paint also crack but only in stress areas or in areas not properly done.
Last edited:
No sign of Mould/Algae. Going to dry them out for a week, as been bucketing down here, then an oil based primer , then Superdec. I assume when it has been gone over with a wire brush and Power washed it will not need sanding again?
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
