Beeck Silicate Paint

[paulb33]

Hi Folks,

I'm exploring use of Beeck Silicate Paint on our 1901 roughcast render. I've dropped the suppliers a note, but wondered if anyone here has any thoughts on whether it might be suitable?

I understand that careful preparation is needed. But, what concerns me most is how it will handle the 'granular' surface. Specifically, its inevitable that it will pool in the nooks and crannies. Will this interfere with curing? Thats what discouraged me from applying a simple limewash.

Value any thoughts.

Paul

 

[malcolm]

Haven't a clue - I'm way away from organising paint for my own render, though Silicate seems very much in the mix of choices to consider in the future.

A lot of the worry for me is paint removal 30 years in the future once it has failed in some way. There are many coats of various paints on my soft bricks. The coating has failed and needs to come off.

The paint removal people say lime paint is very difficult to remove as it cures to rock. Would needs blasting which would ruin my soft bricks if I was unlucky enough to have anything other than modern paints. Is silicate paint any easier to remove?

 

[Flyfisher]

Interesting question. I've assumed it's a bit like limewash in the sense that is doesn't really 'fail' as such rather than gradually weather away, so a bit of a clean-up with a stiff brush and just re-paint (or re-limewash). But that's just a guess because I eventually shied away from silicate paint on our kitchen extension and used limewash in the end and I'm interested to see how long it lasts.

As a new build, it didn't need to be limewashed for breathability reasons but I eventually decided on the basis that it would better match the original walls, which unfortunately have suffered the ravages of 'snowcem' type paint so I'm having to deal with that now rather in your admirably forward-looking 30 years.

 

[Keithj]

I've used Beeck and am very impressed. I'd use it again.

I used it for the NHL plinth round my house after the repairs were done. It looks good and is a lot tougher than the limewash nearby.

The finish is calcium silicate, which is far harder than calcium carbonate, and likely to last for a very long time. The manufacturers won't give you a "life expectancy", but it's a lot longer than limewash.

It is pretty much the standard treatment for lime render in parts of Germany. I've heard of houses over there that haven't been re-treated in decades or longer.

Some words of caution:

1. It works by chemical reaction (much like lime where calcium hydroxide reacts with carbon dioxide to make calcium carbonate and water). However, the end result with Beeck is calcium silicate - harder than calcium carbonate but similar in performance. BUT the reaction is not reversible, whereas limewash is just so much more (tinted) calcium carbonate. Once applied, there's no getting Beeck off unless you remove the lime render and start again.

2. It has to be applied correctly. The process isn't straightforward! Beeck's UK agent will send you some instruction sheets, translated from German. It helps a lot if you speak German and can read the originals (they are on Beeck's German website). The critical and delicate part is that you have to remove the "sinterskin" from the lime before you apply Beeck, or it will fail. That is done with acid, which chews off the skin. Hence, apply acid, time on a stopwatch (it's seconds, not minutes) then hose it off again with plenty of water. There are several more steps in the process, but that's the scary one. It is essential to follow the instructions precisely, even if they look strange (I was only obeying orders...)

3. The active ingredient is sodium silicate (Na2SiO3) which will react in lively fashion with glass (so don't get it on the windows!). Don't try to store it in a bottle. It is also a good idea not to get it on your skin or your glasses. Rubber gloves and delicate care worked for me.

4. The stuff can't be tinted with standard dyes (well, it can, but the colours won't be what you were expecting). The UK supplier can tell you what colours are available.

5. It goes on very much like limewash. If you can limewash, you can do this. It splashes much like limewash if you are too exuberant!

6. You can't stop half way along a wall and come back tomorrow. If you do, there will be a line in the finish where the two coats meet. I don't fully understand the reason why, but I can confirm the instructions were right. The second, all-over coat on mine is fine.

7. It's not cheap.

There is a similar product, called Keim, which we were planning to test on a small panel on the church (Grade I listed) with a view to using it all over if it worked OK. After 18 months we gave up, because the wall was never dry enough to apply the Keim. Beeck didn't seem so fussy about the wall being bone dry.