# Acrylic sement vs silicone



## magneto (Jun 18, 2015)

Hi. I've decided that since I love building enclosures so much, and since I think I'm fairly skilled at it,  I'm thinking of building a few and see if I can manage to sell them. Partly just for the heck of it, and partly to try to battle the increasing cost of this hobby.

Anyway. I've only used silicone (tec7) to glue and seal my acrylic enclosures. It works fine, but the tubes it comes in does not allow for small enough stripes. Witch means the joints can sometimes get a bit messy. And the fact that the silicone stays a little sticky for several days means that it is more likely to get dirty and ugly in the process.

I've seen videos and pictures online of enclosures made by professionals and the joints are practicly invisible. Most of these guys say they use acrylic sement to glue the enclosure together.

Now, my question is: Does anybody have any experience with both? Are there any big advantages to using acrylic sement instead of silicone? Or are the guys in the videos I've watched just that good at making the joints invisible regardless of what they use?


----------



## The Snark (Jun 18, 2015)

Peas and apples. Acrylic 'cement' isn't a cement or glue, it's a solvent. It creeps into and fills any acrylic joint creating one solid piece, if somewhat weaker than the components. It's best application is picture perfect completely smooth surfaces. It won't hide any flaws or rough cuts and cannot fill voids. They come in varying mixtures that effect how fast they dry. I worked with a 'speed solvent' that dried within seconds while normal household types take up to several minutes.

Silicone goo, of which there are several thousand flavors, are gap and joint fillers with the bonus of offering bonds. Commercial applicators consist of a gun with various size interchangeable nozzles, a reservoir and a pressure source. Some applicators deliver micro thin lines but pack several hundred pounds pressure to get the stuff out the nozzles.

Silicone glues are very temperature and humidity sensitive. The higher the humidity and colder the temperature the slower the setting. Damp enough and cold enough it will never set, eventually turning into a grease like substance. Getting it to set is getting it's solvent, various forms of acids, commonly acetic acid compounds, to evaporate. 

Working with acrylic is all about ultra precision cutting and prep. That can entail some pretty expensive tools if you want the invisible seams and connections. Done right using the solvents will be stronger than glues with similar bearing surface areas. 

As a final note, always use fresh acrylic. As the stuff ages it becomes more brittle and harder to make ultra clean cuts. And of course, there are a LOT of different acrylic sheets with varying properties. Some come with manufacturer recommendations for certain types, speeds, of solvents and the environments to store, cut and weld.

Reactions: Like 2


----------



## magneto (Jun 18, 2015)

The Snark said:


> Peas and apples. Acrylic 'cement' isn't a cement or glue, it's a solvent. It creeps into and fills any acrylic joint creating one solid piece, if somewhat weaker than the components. It's best application is picture perfect completely smooth surfaces. It won't hide any flaws or rough cuts and cannot fill voids. They come in varying mixtures that effect how fast they dry. I worked with a 'speed solvent' that dried within seconds while normal household types take up to several minutes.
> 
> Silicone goo, of which there are several thousand flavors, are gap and joint fillers with the bonus of offering bonds. Commercial applicators consist of a gun with various size interchangeable nozzles, a reservoir and a pressure source. Some applicators deliver micro thin lines but pack several hundred pounds pressure to get the stuff out the nozzles.
> 
> ...


Thanks. I'll try the solvent then. I just ordered a tin of Acrifix (same as Weld-On witch I couldn't get here). But dang it's expensive, $169 for a 1kg tin. At least I'll have enough to last years. 

How is it with fumes and the like during the welding? Should I wear a mask? Do it outside? Should I relocate my dubia colony witch is currently in my workshop? Will there be any imidiate danger of my cat dropping dead in the next room? That sort of thing.


----------



## The Snark (Jun 18, 2015)

1 KG? The stuff has a limited shelf life I think. About 2 years? Should be an MSDS available from the company who made it.


----------



## magneto (Jun 18, 2015)

The Snark said:


> 1 KG? The stuff has a limited shelf life I think. About 2 years? Should be an MSDS available from the company who made it.


 Thanks. Well the only kind they had in smaller containers was a thicker syrupy kind that came in tubes. The one kg one is water thin, wich I imagine is much easier to work with. And about the shelf life, if it last me 2 years it's only cost me 20 cents per day then...not so bad.


----------



## The Snark (Jun 19, 2015)

Since you have that much cement you can experiment and practice a bit. Get used to how the stuff creeps and how well with two pieces of plastic held firmly and loosely together, it's properties when the bonding surfaces are less than perfect and so on. Getting familiar with how the stuff works goes a long way to making really nice looking seams and joints. Also, the use of gloves is recommended with the stuff.
With many joints you can hold the two pieces together in finished position then add tiny drops of the stuff along one edge. It should creep between the pieces with ease. I've seen it creep as much as 1 inch into a joint. It's pretty amazing.
The major error people make is using too much of the solvent; it runs all over and crazes or distorts the plastic. Learn how much creep and coverage you get from a single drop and so on.


----------



## magneto (Jun 19, 2015)

Oh I will. I have lots of small leftover bits of acrylic lying around so I plan to do just that. In addition to using a paintbrush I've heard of people using syringes too, so I'm gonna try both methods.


----------



## The Snark (Jun 19, 2015)

An insulin syringe with a fine blunt needle. Gets it right into the joint without going all over. Try relying on creep getting it between pieces (capillary action) instead of painting a surface.


----------



## magneto (Jun 19, 2015)

The Snark said:


> An insulin syringe with a fine blunt needle. Gets it right into the joint without going all over. Try relying on creep getting it between pieces (capillary action) instead of painting a surface.


 Thanks for the tip. I'll look for one after work.  Then I'll just have to wait a week for the sement to arrive...sigh...

---------- Post added 06-19-2015 at 11:45 AM ----------

Update: I just found some at the local pharmasy. They can hold one ml and the hole at the tip is 1,2 millimeter. The hole still looks a little big to me but the only thing with a smaller tip was the kind with the needle on them and i think they are a bit too thin if I'm gonna be able to suck the stuff into it.


----------



## The Snark (Jun 19, 2015)

Try and find a 21 gauge blunt needle. That's about perfect. If you can connect to a good pharmaceutical supply house and some hobby stores, syringes up to 5cc and blunt needles are extremely handy. You can tailor your applicator to what you are doing, the overall amount of cement to be used for an entire job, and how precise and deft you are. Blunts are usually not restricted.

For example, if I was building an entire terrarium around 12 inches square I'd grab a 3 or 5 cc and a 21 blunt which should be enough for the entire job. And needles come with hermetically sealing caps as a bonus. You can also keep precise track of how much cement is needed. A quarter inch thick 10 inch long corner seam will take exactly X amount of cement for a very fine precise weld. That will help you keep from overdosing and making a mess.

It can take a little practice operating a syringe with one hand in all positions. Practice with water. Thumb on plunger, ball of finger on plunger, fingertip on plunger and so on.


----------



## magneto (Jun 19, 2015)

The Snark said:


> Try and find a 21 gauge blunt needle. That's about perfect. If you can connect to a good pharmaceutical supply house and some hobby stores, syringes up to 5cc and blunt needles are extremely handy. You can tailor your applicator to what you are doing, the overall amount of cement to be used for an entire job, and how precise and deft you are. Blunts are usually not restricted.
> 
> For example, if I was building an entire terrarium around 12 inches square I'd grab a 3 or 5 cc and a 21 blunt which should be enough for the entire job. And needles come with hermetically sealing caps as a bonus. You can also keep precise track of how much cement is needed. A quarter inch thick 10 inch long corner seam will take exactly X amount of cement for a very fine precise weld. That will help you keep from overdosing and making a mess.
> 
> It can take a little practice operating a syringe with one hand in all positions. Practice with water. Thumb on plunger, ball of finger on plunger, fingertip on plunger and so on.


 I really appreciate you sharing all your knowledge here mate. It's gonna save me a lot of both time and money, so thanks a bunch. 
Do you know a place online that sells the kind of syringes you mentioned?


----------



## The Snark (Jun 19, 2015)

magneto said:


> I really appreciate you sharing all your knowledge here mate. It's gonna save me a lot of both time and money, so thanks a bunch.
> Do you know a place online that sells the kind of syringes you mentioned?


Sorry but no clue. I buy them from phamacy's. Usually dirt cheap. Syringes, $1 each. Blunts about 60 to 80 cents ea. I'd hope a hobby shop wouldn't scalp you too bad.

By the way. Syringes are made from ultra super duper space age impervious plastics but I wouldn't bet on them holding a solvent for too long.


----------



## magneto (Jun 20, 2015)

The Snark said:


> By the way. Syringes are made from ultra super duper space age impervious plastics


 Wow...what a name!

Thanks anyway. I'll look around here and see if I can find someting similar. Could you maybe snap a photo of the ones you use and post it here so I can be sure what I'm looking for and to show it to the people in the stores? Thanks.


----------

