The important thing is that the surface you are going to cast against is clean from paint and such. Then you can "roughen" the surface so it becomes uneven (chiseling a bit/tapping with a chisel) the more uneven, the better adhesion. Then clean the surface from loose material (e.g., brush with a wire brush). After that, it's time to dampen/wet the old concrete surface (it's suitable to do this while building the form). Old concrete absorbs a lot of water. If you don't wet the old surface, it will absorb the moisture from your new concrete casting, as I mentioned earlier. Once your newly cast plinth has dried (wait at least a month, my tip), you can possibly use the primer you were asking about if it matches the paint you are going to use.
I would not use primer, I prefer to wet the old concrete and cast directly against it without any primer.slacker said:
Unless the product description specifies that a specific primer/or equivalent is needed between it and the old surface. But with regular fine concrete, no primer is needed for casting together.
There is nothing mentioned in the proposed primer's product description about using it for casting against an old concrete surface.
The principle is probably the same since the primer should be diluted with water - However, I believe that using a primer results in even better adhesion as loose particles are glued down. Especially on porous surfaces - Now I guess that TS's floor is not particularly porous so both solutions might work. However, I would have gone with primer!R roli said:
Well, then it's up to TS to choose what he wants to do. With or without primer. If he chooses primer, the suggested one might not be the right product as it seems more like a primer before painting and not a primer for casting directly against. I know what I would have done and @slacker knows how he would have done it.....
Even I'm unsure if that's the right product when I look at the one linked to - Seems to be scant information on this one - It mentions "Målning" which undeniably feels like the wrong product. Poor experience with Byggmax products from Midun, I used their floor lacquers in the cabin but that floor isn't used as frequently as at home so I can't comment on the quality.
I exclusively use Finjas product system when it comes to Primer/concrete/self-leveling compound and gypsum mortar... That's probably the most frequently used.
I exclusively use Finjas product system when it comes to Primer/concrete/self-leveling compound and gypsum mortar... That's probably the most frequently used.
Thank you, Familj Byggahus, you are awesome!
I'm going to start working now, in the recommended cement bag it says nothing about mixing with sand, 6L of water for 25Kg, my bucket isn't big enough to mix 25Kg at once so I'll mix half a bag at a time with about 3L of water.
I'm going to start working now, in the recommended cement bag it says nothing about mixing with sand, 6L of water for 25Kg, my bucket isn't big enough to mix 25Kg at once so I'll mix half a bag at a time with about 3L of water.
Cement bag? You were recommended to buy "fine concrete." No ready-mixed concrete bag requires adding 6 liters of water (as far as I know), it's usually about 3 liters for a whole bag. If you've bought pure cement, it won't turn out well. Mixing it with water will only result in "slurry." If you have cement, you also need to mix in sand and gravel/stone in the right proportions, otherwise, it won't work well.
Everything seems to be fine thanks to you who patiently guided me through all the steps, now I have two more questions:
Thanks in advance!
- When can I remove the tree frame? I poured the concrete yesterday (Saturday) around 2 PM.
- When can I paint the concrete with color floor paint? It must be fully cured for the washing machine and dryer next Saturday, right?
Thanks in advance!
The longer you wait to remove the formwork, the better; the most important thing now is that everything is thoroughly moist/wet. This way, the concrete cures best. You can usually tell when it's time to remove the formwork. When a small crack appears between the formwork and the concrete, you can start considering dismantling, but the concrete is still a bit "fragile," meaning bits can easily chip off at the edges if it takes a hit. Full strength is achieved no earlier than 4 weeks. However, it can be loaded earlier but with caution at the edges. As for painting the surface, you should wait; all moisture must exit the concrete; otherwise, the paint will peel off later on. How long you should wait is hard to say, but at least 4-5 weeks, probably longer. Although your casting isn't thick, if you want a good end result and paint that sticks, I would wait.