Where to buy water clear silicone sealant, which won't cost arm and leg?
CuriousOne
Posts: 931
Hello.
I need a water clear silicone sealant to cover leds in certain application.
So far, found two choices:
http://www.amazon.com/Loctite-5620-Silicone-Sealant-Cartridge/dp/B004RIDII2/ref=sr_1_1?ie=UTF8&qid=1430630432&sr=8-1&keywords=loctite+5620
$100 per 400ml cartridge.
http://www.amazon.com/C-R-LAURENCE-Water-Silicone-Sealant/dp/B006JFM7HY/ref=sr_1_1?ie=UTF8&qid=1430627347&sr=8-1&keywords=water+clear+silicone+sealant
$35 per 310ml cartridge.
Both are way too expensive.
Any idea where to get cheap, water clear silicone sealant?
I need a water clear silicone sealant to cover leds in certain application.
So far, found two choices:
http://www.amazon.com/Loctite-5620-Silicone-Sealant-Cartridge/dp/B004RIDII2/ref=sr_1_1?ie=UTF8&qid=1430630432&sr=8-1&keywords=loctite+5620
$100 per 400ml cartridge.
http://www.amazon.com/C-R-LAURENCE-Water-Silicone-Sealant/dp/B006JFM7HY/ref=sr_1_1?ie=UTF8&qid=1430627347&sr=8-1&keywords=water+clear+silicone+sealant
$35 per 310ml cartridge.
Both are way too expensive.
Any idea where to get cheap, water clear silicone sealant?
Comments
http://www.thomasnet.com/
You might find that the high cost is justified by packaging, promotion, and advertising. Just buying larger caulking gun tubes of clear silicon from a building supply may be adequate.
The general trend in price of paint, glue, and sealents is that there is a optimal price at a larger quantity and these tiny quantities have penalty pricing due to more packaging, promotion, and distribution costs. They also may have a big jump in profit margin to encourage retailers to stock them.
Just buying the branded product can add a huge cost. The reality is most of the silicon sealant is sold in bulk from a few chemical factories that allow the packagers to brand and promote as they wish. Look for generic, cheapo product in a local paint store that sells to professional painters or a local glass shop.
EBay seems to always be cheaper than Amazon, and a good indicator of what is available.
http://www.ebay.com/bhp/clear-silicone-sealant
Unfortunately, "clear" is not same as "water clear". The "clear" one dries semi-transparent, watery milk color, while "water clear" remains clear like water
Andrew, some reviewers on Home Depot's site said it turned yellow when used outside - probably not an issue indoors -
http://www.homedepot.com/p/Loctite-Polyseamseal-10-fl-oz-Clear-All-Purpose-Adhesive-Sealant-1675279/202699069#customer_reviews
Your memory is good.
http://www.tapplastics.com/product/mold_making_materials/casting_products/easycast_clear_casting_epoxy/386
Glad you said something. I was about 16 hours from potting some expensive diodes and capacitors in RTV. Now I'll be sure to use Dow 737 or GE II.
Doing a little reading, apparently it's not just the potential reaction between acetic acid and Cu or Ni that would have been a problem. There is also the fact that acid-cure RTV doesn't stick to acrylic well. This is useful to know because the capacitors and diodes were to be mounted on a Plexiglas panel.
http://www.homedepot.com/p/DAP-2-8-oz-Silicone-Aquarium-Sealant-00688/100128841
Way back in the 1970s, I was studying architecture and helping to build an all plastic geodisc dome. A debate evolved about the best way to construct seams that would be perfectly clear and a letter was sent to 3M asking what to do.
Their reply was rather matter-of-fact. All plastics will yellow when expose to UV light over long periods of time.
Transparency and material aging is a huge challenge -- glass discolors with age, so does plastic. Water clear silicon may be purer or better enhanced, but ultimately I suspect nothing is perfect.
So the question is what is the "certain application".
Plastics and outdoors don't get on well together. A major problem is UV from the sun which tends to fade, discolour, cloud most plastics (and most other things as far as I can tell). My Citroen BX19 GTi was a bright red when new, after 5 years or so the plastic bonnet (hood for yankies) had faded to a very pale pink.
A 10 year old car with red paintjob that hasn't been parked in a garage when not in use will have a horribly faded paint almost no matter what you do.
(New paints are better, but it still fades faster than other colours)
The 'plum red' paintjob on my 16 year old Berlingo, though, is still fine...
Can't remember that my Citro
I tend to lean more towards a water clear epoxy than a silicon. It may be easier to purchase is small quatities at a reasonable cost and may have a longer history to verify how to use it. Not all epoxy is rock hard, some can actually be much softer, almost rubber like.
Bright sunlight and plastics?
Certainly a problem. Here in the sub-tropics we have thousands of plastic motor scooters on the roads, and some of them actually display a special kind of sun rot, where they begin to crumble after years of being parked in bright sunlight on the street.
I am still wondering if carbon fiber will stand up better than most. Carbon black is a preferred stabilier of plastic.
++++++
In the USA, a red car is not a good choice for men. The police stop red cars more often as they expect the drivers to be a bit more reckless. But the police will generally be more tolerant with a women in a red car. One suspects that it gets all a bit flirtatious.
A quarter gallon clear expoxy, good enough for lenses... $34.42USD.
The thing is that you buy in bulk and being A and B components, it has a much longer shelf life onces used partially. Silicon caulk may actually produce a lot more waste as all of it begins to set once opened.
If anyone wants coating for PCB and electronics components, I suggest to use 1B73 from Humiseal - does it's job fine, and even can be re-soldered later (it melts from heat and then covers things again.
I've tested various silicone sealants for direct sunlight exposure, I've taken the opaque white, "clear" one, black one and "high temperature" red one. Applied them to roof and left for one year under direct sunlight. Opaque white shrunk, cracked and almost all went away as dust. Clear was totally wiped out by wind, black developed some holes and rough surface, red was looking just like it had been applied yesterday.
My application is humidity sealing while being non-visible, such as making non-waterproof led strip waterproof (I know clear heat shrink tube trick - I don't like it) and so on. None of them will be exposed to direct sunlight or whatsoever.
-Phil
If acetic acid is a problem, skip the DAP aquatic silicone - it carries a warning "Acetic acid is evolved when product cures..."