I have applied Venze primer over top of knock/down, then finished a nice Venze sample. Looks fine.
The texture is picked-up in the final look.
Chris

I'd skim it out with joint compound, prime with acrylic, then follow the steps for plaster.
10 bucks for a five of mud.

Hi Phil,

Good to hear from you in the UK!

Yes, it is similar to Artex. Artex has many different looks, but the result is the same--a textured finish.

David

YES
Knock/down is a drywall compound type product.This product is mixed with water.Then sprayed on raw drywall under pressure to give a heavy splatter effect.Then prime and paint.
We spray this texture in many diffrent ways.
Such as heavy,light, less background or more background effect.
I have even hired guys to work behind the spray truck to trowel into the wet material to give a troweled effect.
This product(knock / down ) can have drywall mud applied over it ,to make the walls smooth again.This is what we call a level 5 finish.
This takes 3 coats to get the area completly smooth with out any flaws.(ready for Paint)The first coat takes the most compound then each coat takes less and less drywall compound.
I found appling Venze primer or pronto over knock down was easyer then 3 coats of compound.I dont mind th extra cost of products compared to the extra labor.But the final effect i find to be more diffrent with the Venze primer than the pronto.The pronto seems to cover the knock down better
I guess Scott and I, agree to disagree.

I agree to agree to a degree,

I prontomuro right over splatterdrag then darby.
I have not done it with Veneziano yet but probably
would. I never tried pronto-darby over orange peel
probably to bumpy with the raised areas, I have found
that the prontomuro is an excellent filler for knock down
and if troweled evenly it darbies great.

Chris, the Black Hole is great I loved it. I bet it looks
great in person in that house with that effect.
Modern Art.

You know the texture I hate the most. The windshield wiper
effect where you turn your blade and pull the mud to a
stop creating a line of thick mud the size of the blade.
Wierd look.

Vallie

Thr black hole is amazing. People are actually getting dizzy stairing at it. HaHaHa.

Chris,
I had to show my husband your black and white wall because it was so cool. He loved it too. I wouldn't mind using a close up for a screen saver. Way cool.

Thanks for your support. I enjoyed doing the wall.
There is a large group of people who i come across ,that love the black and white interiors.
Chris