Hot Property
Well-known member
My mate "Robert" who is a builder thinks we should all use Gripfill..........
Sika flex vs DIY Store Silicone
- Thread starter jrudge
- Start date
bluetooth
Active member
And what's best for resealing external windows ?
My 2002 windscreeen is leaking a little; taking the whole front windscreen out is, so I am told, not practical / possible. Was thinking of sealing over the hard rubber. Any thoughts ?
Cheers
My 2002 windscreeen is leaking a little; taking the whole front windscreen out is, so I am told, not practical / possible. Was thinking of sealing over the hard rubber. Any thoughts ?
Cheers
dragoon
Well-known member
And you become the proud owner of a tube that looks like black worms have protruded from its sides
it definitely works though!
dragoon
Well-known member
That sounds like a good idea also. I may try that next time I open a new tube.
dragoon
Well-known member
I would start with some Captain Tolleys crack cure. It's transparent and will go deep into any crevices. Makes sure to wipe any excess with a wet cloth as it dries though. Only if that doesn't work would I start applying the black gunge - but it can be done with Sika- at least I've used it in that way on the boat and my Landie. From memory the 291i is UV resistant but check before use.
dragoon
Well-known member
piston
New member
I think we're talking different disciplines here. I build fibreglass boats, hardly any wood in them, and certainly none on show, and not a drop of paint or varnish used. You're obviously talking wooden boats, so I can understand the aversion to silicone.
stelican
Well-known member
I have found that an opened tube of sika will stay useable for 6 months if kept in a fridge
dragoon
Well-known member
I too have avoided silicones, both for wood and fibreglass as it's never struck me as durable and doesn't adhere like Sika. I also find the smell repulsive. In the past I used it in industry for sealing body o-rings on submersible pumps, but in retrospect I wonder if it was the right stuff.
My boat is 37 years old and over the years I've stripped and replaced most things, but I've never come across any silicon sealants. Butyl yes, but not silicon.
dragoon
Well-known member
I've heard that before, but I don't think I'd be allowed!
bluetooth
Active member
Better than a tortoise! Is in beer fridge for safe hibernation mind!!
PCUK
Well-known member
My Sika is in the freezer. Strangely it is very soft and easy to extrude when used freezing cold!
Tk24a
New member
Sorry I am a tad late to the party but thought I’d add my two cents if it helps anyone. I’ve had experience in the building, industry and boats construction for a few years also.
Sika is amazing stuff. It sticks and bonds incredibly and can be painted over which in so many cases makes the decision for you..
However, during my research, I discovered that Sia flex (polyurethane), is an organic compound and begins to break down around the 10 year mark (exterior application presumably due to UV).
Painting over would help this a lot of course.
Silicon on the other hand is a synthetic compound that has a lot more hardy chemical structure and is supposed to last around the 20 year mark even when exposed to the elements.
Silicon gets a bad name from the outrageous percentage of people who apply it incorrectly. It’s nowhere near as sticky or viscous and therefore does not relax onto the surface and engulf the dust, etc, making a bond to be reckoned with.
Make sure you’re carrying lots of heavy duty, wet wipes, or a spray bottle of isopropyl with several rags as it really does get everywhere.
Silicone, you can get away with spit and a finger (or water and detergent in a spray bottle) if you are dignified.
I still prefer Sikaflex myself as besides the longevity inferiority it is far superior in every way. And if you use the right paint and thickness you may be able to make the sika last just as long.
A good testing ground for roof and guttering (a true test of durability is Australia due to our record setting UV exposure and high temperatures (causing ridged materials to expand and distract, disconnect from some sealants.. Silicone for exposed joints or quick fixes and sika for bond sealing or anything that needs paint.
Use a UV resistant paint and you’ll be laughing.
If you’re not experienced with sickaflex, please learn from my (and every apprentice I’ve ever trained even after clear instructions and warning)
Use disposable gloves and double/triple up so you can pull one off when it’s dirty.
Carry lots of industrial style wet wipes.
Carry isopropyl alcohol in a spray bottle along with rags and depending on what you’re doing some shaped application tools to create these beautiful rounded beads. (I can do a better job with my finger, but some of those tools are quite good at both removing old, silent and providing a beautiful finish to your new job).
Painters tape to get your straight lines and not contaminate the area.
(This is for Sika only.
When using silicone all you need is a finger and some spit. Or some isopropyl and a wet wipe to clean your finger if you want to go all out.
Most important thing when using silicone especially is to prepare the area perfectly. Wipe off all dust. Use alcohol to get rid of any oil or grease.
If the area is glazed or shiny plastic, painted or polished metal, you will need to rough this up to some extent to create a real bond.
I either hit it with a wire wheel on my drill or if that’s not possible just scratch the shit out of it with a Stanley knife or rough sandpaper. A few Cris cross patterns with a fork will do fine.
I’ve gone back to countless jobs to fix other peoples installs where they did everything perfectly, but the whole switchboard was filling with water. Turned out when I took the box off the huge amount of silicone they had used just peeled straight off like it was stuck to waxed baking paper.
When applying, squeeze very slow and drag the nozzle in a circular motion (half once diameter) as you go, so it picks up any dirt dust, and debris left behind. You will see why this is necessary as soon as you start, and you will know straight away when you completed that step.
Once the entire area you wish to seal has that reliably stuck basecoat of silicon on it, you can apply your proper desired bead over the top of it when its still wet.
I usually do the same for the surface I’m sticking it too but depends on the surface.
A high-powered blower will usually be enough if it’s just rough brick with some dust on it.
Might sound overboard but that’s the way to get the best results.
My apprentices can’t be bothered with all that stuff despite my multiple explanations but I’m hoping I’ve helped you in some way at least.
Ps: I have been known to seal a gap with silicone and then when I’m done I’ll go over it with sika flex.
I have no idea if that might cause a reaction or be detrimental in anyway, the logic being the silicon will last longer than 20 years given that it’s completely protected from UV and the weather, sick flex on top. Will provide a more durable seal that can be painted and is less likely to be damaged.
Sika can also be sanded and it creates a significantly stronger bond and protective surface than any silicone I’ve seen.
Not all, but some specific silicon can be used underwater and in rain.
Never use normal products on wet surfaces, to the extent that even a completely dry looking concrete roof tile after rain will still not create a good bond. You will need to hit it with a gas torch and watch all the water evaporate out before application.
Happy sealing xx
..Tim
Sika is amazing stuff. It sticks and bonds incredibly and can be painted over which in so many cases makes the decision for you..
However, during my research, I discovered that Sia flex (polyurethane), is an organic compound and begins to break down around the 10 year mark (exterior application presumably due to UV).
Painting over would help this a lot of course.
Silicon on the other hand is a synthetic compound that has a lot more hardy chemical structure and is supposed to last around the 20 year mark even when exposed to the elements.
Silicon gets a bad name from the outrageous percentage of people who apply it incorrectly. It’s nowhere near as sticky or viscous and therefore does not relax onto the surface and engulf the dust, etc, making a bond to be reckoned with.
Make sure you’re carrying lots of heavy duty, wet wipes, or a spray bottle of isopropyl with several rags as it really does get everywhere.
Silicone, you can get away with spit and a finger (or water and detergent in a spray bottle) if you are dignified.
I still prefer Sikaflex myself as besides the longevity inferiority it is far superior in every way. And if you use the right paint and thickness you may be able to make the sika last just as long.
A good testing ground for roof and guttering (a true test of durability is Australia due to our record setting UV exposure and high temperatures (causing ridged materials to expand and distract, disconnect from some sealants.. Silicone for exposed joints or quick fixes and sika for bond sealing or anything that needs paint.
Use a UV resistant paint and you’ll be laughing.
If you’re not experienced with sickaflex, please learn from my (and every apprentice I’ve ever trained even after clear instructions and warning)
Use disposable gloves and double/triple up so you can pull one off when it’s dirty.
Carry lots of industrial style wet wipes.
Carry isopropyl alcohol in a spray bottle along with rags and depending on what you’re doing some shaped application tools to create these beautiful rounded beads. (I can do a better job with my finger, but some of those tools are quite good at both removing old, silent and providing a beautiful finish to your new job).
Painters tape to get your straight lines and not contaminate the area.
(This is for Sika only.
When using silicone all you need is a finger and some spit. Or some isopropyl and a wet wipe to clean your finger if you want to go all out.
Most important thing when using silicone especially is to prepare the area perfectly. Wipe off all dust. Use alcohol to get rid of any oil or grease.
If the area is glazed or shiny plastic, painted or polished metal, you will need to rough this up to some extent to create a real bond.
I either hit it with a wire wheel on my drill or if that’s not possible just scratch the shit out of it with a Stanley knife or rough sandpaper. A few Cris cross patterns with a fork will do fine.
I’ve gone back to countless jobs to fix other peoples installs where they did everything perfectly, but the whole switchboard was filling with water. Turned out when I took the box off the huge amount of silicone they had used just peeled straight off like it was stuck to waxed baking paper.
When applying, squeeze very slow and drag the nozzle in a circular motion (half once diameter) as you go, so it picks up any dirt dust, and debris left behind. You will see why this is necessary as soon as you start, and you will know straight away when you completed that step.
Once the entire area you wish to seal has that reliably stuck basecoat of silicon on it, you can apply your proper desired bead over the top of it when its still wet.
I usually do the same for the surface I’m sticking it too but depends on the surface.
A high-powered blower will usually be enough if it’s just rough brick with some dust on it.
Might sound overboard but that’s the way to get the best results.
My apprentices can’t be bothered with all that stuff despite my multiple explanations but I’m hoping I’ve helped you in some way at least.
Ps: I have been known to seal a gap with silicone and then when I’m done I’ll go over it with sika flex.
I have no idea if that might cause a reaction or be detrimental in anyway, the logic being the silicon will last longer than 20 years given that it’s completely protected from UV and the weather, sick flex on top. Will provide a more durable seal that can be painted and is less likely to be damaged.
Sika can also be sanded and it creates a significantly stronger bond and protective surface than any silicone I’ve seen.
Not all, but some specific silicon can be used underwater and in rain.
Never use normal products on wet surfaces, to the extent that even a completely dry looking concrete roof tile after rain will still not create a good bond. You will need to hit it with a gas torch and watch all the water evaporate out before application.
Happy sealing xx
..Tim