Silicone jargon - explanation required

[Handyman]

In the world of silicone sealants, can anyone tell us what is meant by:

High modulus
Low modulus
Neutral cure
What are the differences between "sanitary ware sealant", "kitchen sealant", and "building sealant"?

And where can I buy that seriously tough silcone rubbery type sealant like they use to seal between concrete blocks on sea walls and other major concrete block type constructions?

 

[fitter]

Sounds like you have a real serious project coming up.

 

[Handyman]

Yes: Stone/concrete retaining wall against back wall of warehouse. Wall is 2.1m high, 0.5m thick, and 40m long. Wall has two wide vertical cracks (up to 25mm) which reach to the top and back of the wall. Wall is otherwise pefectly sound (and about 100 years old). Cracks allow water to ingress at top of wall and make the back wall of the warehouse damp. My (cost effective) solution is to inject heavy duty silicone into cracks and cap off cracks with mortar. So, where can I get this HD silicone?

And what do all these other silly cone terms actually mean??

 

[masona]

I know what you want but I can't remember the name of it.

We have a flood wall around the refinery and they use 25mm grey rubbery mastic type between each section.

Sorry I can't be much help but you could try and ring around for construction engineer company or a good builder merchant might be able to help you.

Another thought maybe a Cement Ready Mix company might be able to help you or tell you where to get it from.

 

[BiGDave]

Have a look here http://www.dowcorning.com/

 

[mildmanneredjanitor]

In the world of silicone sealants, can anyone tell us what is meant by:

Here are my guess's!

High modulus
Low modulus

Refers to the viscosity of the product, thick/thin?

Neutral cure

Not sure about this one, sometimes neutral refers to colour (bit like magnolia) but maybe has no active ingredient to accelerate the curing process?

What are the differences between "sanitary ware sealant", "kitchen sealant", and "building sealant"?

Sanitary contains a fungicidal element to prevent the growth of... fungus!

Kitchen and building sealants can usually be cleaned up with water (before it has cured), but a silicone sealant requires a solvent like acetone. Also tend to be less malleable when cured than silicone.

I'm sure Adam the Oracle will correct me!!!

 

[AdamW]

Nah, I know s*d all about sealant other than how to apply it... even then there is some debate

I think neutral cure might refer to the fact that "normal" sealant gives off vinegar (acetic acid/ethanoic acid) as it cures. Hence the particularly pungent odour. Neutral cure probably gives off no acidic or alkaline fumes.

Can't imagine a small amount of vinegar vapour would cause any problems with anythink likely to be used near sealant though!

"Modulus" usually refers to the elasticity of a material, I think that would be the case here. "Young's Modulus" is equal to the Stress divided by the Strain... Basically, the Strain is how much the material can stretch, so if the Strain is greater, the "Modulus" is lower.

So, I would assume "low modulus" sealants are more flexible and can withstand more movement than a "high modulus", but would not be so strong against e.g. finger nails. Which is what The Mild Mannered Janitor said

 

[Handyman]

There's a lot of "I think", "assume", and "??" in your collective answers, but does anyone out there actually know?

For example, glazing silicon is "neutral cure", and from my experience, it just takes longer to set.

Also, the kitchen sealants referred to by mmj which are water-soluble, are not silicone based sealants.

If I knew what these terms meant, I might be better equipped to select the correct product.

 

[mildmanneredjanitor]

Also, the kitchen sealants referred to by mmj which are water-soluble, are not silicone based sealants.

Isn't that what I said?

You try to help...

 

[AdamW]

Well OK, we will all keep schtum whilst someone else explains it all

You should be more cautious if someone says "Hey, I know everything about this". We are all humble enough to make it clear that this is not definitive advice, so if you go and do your project and it all goes t*ts up we aren't to blame! There has been advice given on this website in the past that is just silly and sometimes dangerous, by someone professing to know what they talk about, that is a lot worse than lots of "I think this is correct".

I know that what I said about modulus is correct, but that is the standard engineering/scientific use of modulus. It may be difficult in the world of mastic.

A builder's merchant or the website Big Dave gave us might be able to steer you in the direction of the correct product (maybe ).

 

[Handyman]

I have directed my question to Dow Corning, as per BigDave's suggestion. I will post "definitive" answer here in due course. (Hopefully).

 

[Handyman]

And here it is, from Geocel Limited, the Strategic partner of Dow Corning:

"High and low modulus.
This refers to the modulus of elasticity of the silicone sealant and therefore can be related to the flexibility of the product. High modulus silicone sealants will have a good flexibility, but low modulus sealants will tend to be more flexible, ie excellent flexibility. The lower modulus of elasticity places less stress on the bond line.

Neutral cure refers to the curing type. Generally silicone sealants are either acetoxy or neutral curing. Acetoxy curing products release acetic acid during curing process, therefore may not be suitable for substrates sensitive to acetic acid, this includes metals such as copper, brass and alkaline surfaces such as mortar and concrete. Neural curing silicone sealants do no release acidic products during curing."

QED

 

[aussie1]

just buy the silicone for the job you are doing,It will tell you on the tube where to use it,dont even go into what it is made of.

 

[Handyman]

Ah, but if I'm doing a job and I need to find the right kind of silicone, it's useful to have some initial guidance to narrow down my research for the correct product. In any case, generally, I like to know why as well as what. In this case, now I do.

 

[oilman]

If your wall is 100 years old, it is probably put together using lime mortar, so why aren't you using lime mortar and giving it another 100 years life instaed of using something inappropriate, not unlike a bath sealant? These structures deserve better. Cost effective, er.....cheap and nasty?