Roger Bisby fills us in on some things builders and plumbers commonly get wrong when applying silicone.
The building industry has been using silicone sealants for years now but a surprising number of tradespeople don’t know the difference between high and low modulus or neutral curing. I may upset a few people when I say this but I think this is largely the fault of the manufacturers themselves.
Builders are not chemists and they don’t want a lot of complicated terminology on the tube. Just tell us what it does and where to use it and maybe even where not to use it. Information such as ‘can be used on natural stone and non-corrosive to metals’ is more helpful than simply stating it is neutral curing.
Happily, the makers of HB42 have taken this on board with a well designed and informative pack. Hopefully others will follow.
HB42 will be familiar to PB readers because we have reviewed their polymer-based all-purpose adhesive and sealants.
Quality is important because cheap bargain bin silicone contains a high proportion of fillers which limit the flexibility and reduce the life.
The flexibility (modulus) is important around baths, showers and window and door frames. If you have trouble with silicone pulling away from a surface it is not only due to lack of adhesion, it may also be that the silicone just doesn’t have enough stretch to cope with the movement.
In a bath or shower room you will also want a mould inhibitor in the silicone, though it is important for your customer to know that mould will grow on top of the silicone if it is not cleaned thoroughly and regularly.
The other factor that affects the performance of silicone is how it is applied. The surface should be clean and dry and that is taken as a given, but how clean can you make it?
I have heard of people using WD40 to remove old silicone and then, with a cursory wipe down they expect the new silicone to stick. Thankfully there are now specialist cleaner sprays, such as HB42 solvent spray, which cleans old sealant traces and all manner of grease and gunge.
It is also brilliant for removing chewing gum and other stubborn deposits. One word of warning: Don’t leave it on 
your dashboard or even on the front seat of your van. This product is widely used in the painting industry to make sure the surface is free from any contamination.
I was curious to know how they arrived at the name HB42. The answer is that HB is Hilton Banks and 42 (as fans of The Hitchikers Guide to the Galaxy will know) is the answer to everything.
I kick myself for not having twigged that little bit of trivia but now it is in my head I will be bringing it out as an ‘interesting fact’. My wife will tell you it is the reason I have very few friends.
For more information on HB42 click here.
