Acrylic Bonding Techniques & Aquarium Construction

[acrylic51]

The only drawback to 42 is the cost of the applicator or gun......$300-$400 price range for the gun and that's not including the solvent if cost prohibitive even for me who likes to play........40 is cheaper, although a little more intensive as far as mixing. Strength you'll see no gain vs using 3 or 4 unless you have an oven.....But I fully understand the want to try it out.....Maybe if you hit James up he has in the past been known to rent the guns........
Corey is correct on climate; humidity affecting joints.....That being said where Corey lives definitely not a smart idea to use 3....4 a tad better....This is another thing James touched on a bit in the thread. He doesn't use a "stock" solvent. He makes his own solvent and I don't recall the ingredients, but he does list them. The reasoning behind using or making your own solvent is you can adjust and control the evaporation time or work time more or less.....That is the issue with WeldOn 3.....It evaporates to quickly and with a humid climate is really bad.....4 is a bit slower, but not much.....
What kind of sump are we talking Corey......

 

[2quills]

Quote:
Originally Posted by acrylic51 http:///t/196219/acrylic-bonding-techniques-aquarium-construction/60#post_3515950
The only drawback to 42 is the cost of the applicator or gun......$300-$400 price range for the gun and that's not including the solvent if cost prohibitive even for me who likes to play........40 is cheaper, although a little more intensive as far as mixing. Strength you'll see no gain vs using 3 or 4 unless you have an oven.....But I fully understand the want to try it out.....Maybe if you hit James up he has in the past been known to rent the guns........
Corey is correct on climate; humidity affecting joints.....That being said where Corey lives definitely not a smart idea to use 3....4 a tad better....This is another thing James touched on a bit in the thread. He doesn't use a "stock" solvent. He makes his own solvent and I don't recall the ingredients, but he does list them. The reasoning behind using or making your own solvent is you can adjust and control the evaporation time or work time more or less.....That is the issue with WeldOn 3.....It evaporates to quickly and with a humid climate is really bad.....4 is a bit slower, but not much.....
What kind of sump are we talking Corey......
Not sure, maybe use the sump I already have.
And yep, that's the problem is biting the bullet to get the applicator gun, unless I'm going to get some real long term use out of it. I suppose that I could always sell it if I felt like I was ever done with it. It doesn't seem too terribly easy to get your hands on one those things for cheap.
Actually, I had a fair amount of discussion with the old timer that owns one of the only two plastics fab shops here in, corpus, And he initially turned me on to his mix of #3 and 4 for welding down here. And actually the tanks that I did before the weather turned ridiculously hot actually came out pretty respectable I think. But again, I sacrificed a fair amount of good scrap pieces for practicing making my joints. So, just something to for the diy'ers again to think about.
If I had to build in the summer for purpose I would do so in doors where there's less wet air.
I don't notice a huge difference between 3 and 4 when used seperately. In order to get a clean joint anyways I think you need to be quick about it and not fudge around for too long with either product.

 

[piiqmark]

First what size is the tank your planning and what material thickness are you hinting of......Undersized material will undoubtedly lead to issues with bowing, some more severe than others depending on panel length and height......I've followed a thread on RC a while ago where a guy did a 10' panel with no issues, but I go back to my first question asking about size......
If proper material is selected being thickness and such for the application then no, no additional bracing would be needed at that seam point.....9/10 times when acrylic fails it's not at the seam it usually elsewhere....You can take a 1/2 decent joint that's been glued and try to destroy it with a sledge hammer and the acrylic will break before that joint.....Try it.......
You asked also about euro bracing.....Again this is very dependent on what the size of the tank is and what material thickness your using for the build....If your building something like a traditional 120 out of 1/2" material and want to go rimless.....No way.....The thing would bow like mad.....Now could you build the same tank with same thickness of material and use euro bracing.....Yes, but you'll still have bowing....Material will bow, but not as bad with no bracing.....Now keep in mind that acrylic will absorb some small ratio of water....Over what time period or span who knows, but if you do a little digging you'll see it will.....With that said if you were doing a 120 using 3/4" material you would still want to euro brace, but your bracing could get smaller possibly.....As you step up in material thickness your bracing would follow......Now lets say your building something on the lines of 48"x24"x12" and used 1" material.....Would bracing be required.....IMHO definitely not required......Now also keep in mind that most want aggressive water movement and waves in their tanks.....This is another area that you need to take into consideration when selecting material thickness as well.....
As far a removing mess from acrylic.....Yes and no.....Depending how bad the mess is probably not.....I have in the past been able to sand it out, but this was more a "sprits" when I finished up a joint from the bottle.....Now if your talking about oozing it across the panel, probably not.....I have also when it was so minor taken my torch and hit the spot really quick and gone.....This I don't recommend and it was something I was playing with out of curiosity..........
Thanks for the response! For me it's info gathering at this point. One of the challenges I have is material lengths. I know I can buy stuff online get it shipped or even buy locally and have it delivered but my situation is very unique. I have a family member who works for one of the larger international manufacturers. Its close to 40-50% off on some of the products and at least 35% off on others. So here is the twist, He is in a corporate office and they will only ship a max size 24x48 sheet to his mail room for employee acceptance. So with the price being pretty good and a little bit of "delusions of grandeur" syndrome it has me thinking. I think after the info gathering phase ill take a crack at it. Ive used more acrylic than needed on every fuge i built/helped build (first one was about 30gl and i used 1/2 inch and 3 braces!!! LOL) but I tend to over build everything when safety is a concern. I would think no matter what i build i would brace it and use the next suggested size up from the recommended thickness. So for the sake of giving an idea on size, lets say this: 1" thick 3-48" long sheets to make 144 inches total length, 24" high 24" wide/deep (but maybe get a bug right before assembly and want to go 36" deep -throwing this in there for the other thinkers out there) brace around the edge with 1" thick 3 inch wide around all edges with a cross brace every 24". Would you call that over built or just enough or not enough?
If i were to get serious (im getting close to the serious point) and take on this project I personally think 10' long would be my max, in my little dream world an "L" shape at 18' (10+8) would be a great way to remodel my home office (currently 14X12) anyway great thread folks! Nothing like good info to stimulate the DIY minds!!!!

 

[acrylic51]

Looking at the grand scheme of what you might have in mind.....Time and labor vs cost....You'd be better off buying it local.....You can buy online bigger pieces, but then considering the time an attentiveness to detail could out weigh the cost savings.....For any DT build....Polycast (Spartech) and can't remember the other, but Corey should be able to jog my memory.....I wanna say it's acrylite G.....These 2 and don't quote me on the Acrylite are the only 2 brands recommended for DT builds.....As you mention 1" material costs get quite expensive, so as you shop keep these 2 brands in mind for your use......You can chance other brands, but your major manufacturers won't usually budge from these 2.
Another issue I see with going the smaller panel route is edge prep and cutting of the proper bevels for the seaming.....Doesn't seem like a big deal or chore, but 1" thick material is a PITA to cut.....Unless you have an actual industrial or top quality cabinet saw at home.....Well the "compact" or "jobsite" table saws aren't what you want for the job.....Routers....Again your typical 2hp router can do the job, but remember cost of material and time spent on the project you'll want minimum of 2 3/4hp or bigger.....I did use a 2 3/4hp to cut mine, but you have to keep in mind how thick the material is and you have to make small incremental cuts, so again time comes into play and patience. Again I go back to it might be feasibly more economical to bite the bullet and purchase local if your go "BIG".....Edge prep is killer and it is hard for the DIYer to get a good clean edge without a real setup.....A dedicated router table, and I'm talking full size table or out feed tables to totally support the pieces.....The weight is astonding even cut down to size and for a panel 10' you will need (2) people; yourself an another to handle the pieces and to get them into place while gluing.......
"L" shape you mentioned is totally cool......I sit back at times and wish I had done that with my setup, but to late in the game for me.....There was a build thread over on RC that was done that way, but I think it was done with glass though, but still similar concept.....Again the cuts have to be perfect.......This shape; design presents a unique challenge as far as flow inside the tank.....I remember the thread and it's not as simple as throwing PH's at it.....Because of the "L" shape it presents challenges getting flow moving throughout the tank without dead spots......
Sorry I jump around but ADHD gets to me at times, and might show through my build thread with my concentration at times.....But I'm also anal about details.....You had mentioned 36" depth.....I'm hoping your referring to (front to back)......A nice depth, but trust me once you see it empty you'll say "wow.....that's huge...." You start putting rock work inside and it's not as big as you had envisioned.....48" depth if your going to go through all the trouble and time to build.....Just my .02
Another challenge I see for the "L" design is possibly overflow location.....Again keep in mind that it's not a long fluid line, basically you have 2 separate entities if you think about it since the corner was added into the equation.....I would suggest an external overflow if possible, or worse case and coast to coast overflow vs the traditional corner overflow design......To me a classier look at times, and saves on space wasted inside the DT.....
A lot of food for thought, but some serious considerations......A tip.....Find out your local plastic places and make friends with them......Trust me a little time over at the shop might lead to a little machine time if needed......I bring cigarettes to my buddies Tom & Matt.....Mt Dew works as well......

 

[acrylic51]

Corey Piiqmark did job my memory about that long tank on RC....It was 144" long.......
I also just caught something in Piiqmark post about euro bracing......It's a personal thing IMO about bracing......Material thickness will dictate bracing requirements.....at your proposed dimensions 1" is pushing the envelope......Length is what is going to be the factor......Even with the cross bracing every 24" I still think there's no safety margin and will bow....I could be wrong, but someone might suggest going to GARF's site an using their calculator.....Don't it sucks!!!!!! Personally I try to avoid cross bracing, but there's trade offs.....My biggest thing is lighting.....Most times the cross bracing falls right were you want your lighting.....Not sure on lighting, but definitely wouldn't place MH's directly over my bracing......As far as 3" wide....IMHO not wide enough......

 

[piiqmark]

I think i missed something reading the 45 degree joint. Lets say you had 1 panel that was cut to a 45 and wanted it connected it to a straight factory cut edge, would we lose or compromise structural integrity? Since the thickness of a 45 cut will be less along the one edge do we lose "grip" or would a nice bead of weld on 40 on the inside help? Or, could you use another 45 brace along the top edge/inside to replace and beef up what is lost (if anything) on that 45 turn? This thread has my wheels spinning to much - the mice running on the wheel in my brain are at full steam! LOL
Also, on the straight 48 + 48 example - are you saying you couldnt finish the edges (scrape or sand to take out all the roughness) like you would on a 90 degree connection? Am I reading it the right way? I would have to bevel the edge? Would the reason for the bevel be to increase the surface area covered by the bonding agent? Maybe my ADHD is kicking in! LMAO! Thanks guys!

 

[piiqmark]

BTW, i know you guys were talking 45 to 45 angles - or at least i think you were. I guess my brain was having its own conversation and thast where I came up with the 45 to factory connection. I am thinking of that "L" Shaped tank idea and the water flow challenge. I would assume a combination of 45's would break up some of that flow resistance. If you had the time and skill I guess you could bend the material but that my new found friends is WAYYYYYYY above my skill level. So my thought on an "L" to help with flow would go something like this: Connection 1 flat to 45 connection 2 flat to 45 giving you more of a sweeping "L" shape. Creating sort of a hexagon tank "look" on the turn. Would love to hear your thoughts on that.

 

[2quills]

Piiqmark: my thoughts on if you wanted to make 45 degree angles on your tank then youd be better off making two 22.5 degree cuts vs one 45 butted up to a strait cut. That would give you more surface area for bonding.
If you try and join a 45 to a strait cut then the pieces wont match up properly and you'd have to sand down the edge that sticks out and then polish it to make it look right.
I guess you could always slide and join the pieces up to where the edge wouldn't stick out but in doing so would mean joining them along the tip of the edge where the material is at it's thinist. But in my mind that would be a weaker joint.
Hope that made sense.

 

[piiqmark]

Yeah that does make better sense - wasnt thinking of 1/2'ing the cut to 22.5 which is why i thought of the integrity issue - great point! I know the acrylic tank manufacturers make hex tanks so if i ever get to see one up close I could bet your suggestion would be spot on in their assembly. Unless they form them with heat which is not my cup of tea. Although - I wonder what the average rate someone would pay to have that done for them. Heck, anyone know what it costs to have a sheet bent - 45 degrees or any other degree for that matter? I am in NYC so might be a little higher but sure would save a few headaches!!!
Thanks 2Quills

 

[2quills]

Quote:
Originally Posted by piiqmark http:///t/196219/acrylic-bonding-techniques-aquarium-construction/60#post_3515991
Yeah that does make better sense - wasnt thinking of 1/2'ing the cut to 22.5 which is why i thought of the integrity issue - great point! I know the acrylic tank manufacturers make hex tanks so if i ever get to see one up close I could bet your suggestion would be spot on in their assembly. Unless they form them with heat which is not my cup of tea. Although - I wonder what the average rate someone would pay to have that done for them. Heck, anyone know what it costs to have a sheet bent - 45 degrees or any other degree for that matter? I am in NYC so might be a little higher but sure would save a few headaches!!!
Thanks 2Quills
I'd put a call in to some local shops and ask around about prices.
My guess is that it would be more expensive if all manufacturers built hex tanks by mitering all of the edges. Most of the cheaper/massed produced tanks are primarily heat formed and then have one vertical seam/joint. We see this a lot in acrylic bow fronts as well. More bending = less joining.
My plastics guy down here doesn't build tanks anymore. He said he used to but he stopped after people tried to take him to court twice for damages to their homes from tank failures. He said that fortunately he was able to prove in both cases that there was clear damage indicating the tanks were impacted in a fashion that caused them to fail but not because of poor craftsmanship. So he was fortunate.
Never the less he said he didn't want to deal with tank builds anymore because it wasn't worth it to him. But he told me that he believed the best method for building rectangular shaped tanks is to take a sheet of acrylic and cut each of the 4 corners of the sheet and then heat and fold it up like a box. So essentially you'd have no horizontal joints along the bottom of the tank at all...only the 4 vertical joints in the corners. And then the 4 sides along the top brace. I've never seen it done but he apparently swears by it.
The Problem is access to the same kinds of equipment that he uses in his shop.
Another thing that I've noticed when trying to form acrylic is how it deforms the edges of the piece where it is being formed or bent at. I need to try some different methods though for heating the material other than using a heat gun because it's easy to craze the material. I've seen a guy build is own bending bench for forming formica counter tops where electricity was used to supply the heat along a long metal shaft/tube. The table held the piece and then it had a top piece that folded down which supplied even pressure and force across the sheet I bet it wouldn't be to hard to build similar bender for the purose of using acrylic. I mean they're both plastics right?
There was also a voltage regulator used to control the amount of electrical current supplied in order to adjust the temperature of the heat shaft.

 

[acrylic51]

Hmmmm Acrylic heaters are expensive.....Fortunately I have a 4' heater in the garage.....I don't use it much anymore.....

 

[acrylic51]

Piiqmark I did get your PM, just need time to reread it a bit......

 

[piiqmark]

Quote:
Originally Posted by acrylic51 http:///t/196219/acrylic-bonding-techniques-aquarium-construction/60#post_3516046
Hmmmm Acrylic heaters are expensive.....Fortunately I have a 4' heater in the garage.....I don't use it much anymore.....
So this guy sells a kit http://www.youtube.com/watch?v=ZkjsPrWT0Ic and this guy tells you how to use the wire he sells, this looks to be cheaper option (actually really cheap considering you could get a power supply for less than 100 bucks - 75 on amazon) http://www.youtube.com/watch?v=wVEf7PfuKxo I have also seen some instructionals where they take apart a hair dryer... no thanks on the hair dryer idea! LOL
Here is my issue with getting into something like this: in the second video towards the end he tells you thicker shets need a "V" groove cut prior to heating. While I am fine with that and capable of beading some weldon 40 up the the inside corner of the bend, Acrylic51 makes a great point earlier in this thread about the proper tools (specifically the router). The slightest bend in what should be a perfect straight line screws it up big time. Just like matching the corners on a sheet of paper and folding it. Once you fold it you can never go back to make it look perfect if you screw it up on the first shot. Paper is cheap acrylic, not so much! So this may work for some but I personally lack the confidence to tackle this.
Here is another question related to cutting, or should i say a way around it: If you think of a curved or bow shape, or even 2 45 angles to make a 90, you still have to cut base/floor pieces. Would it be possible to use some form of liquid acrylic or epoxy to form the floor of the tank? Would it bond to the acrylic and create enough strength and support assuming your stand/support structure is capable - think hardi-backer board you use in a bathroom over plywood. Is there such product? First thing that comes to mind is the bartop epoxy but is it thick enough, is it toxic when cured and will (if it does bond) create a strong enough bond to support what we are talking about? For the sake of conversation - lets say you could pour something in to create a bond. A tank of this size would probably never move and its likely in a home you own so construction/deconstruction isnt a problem at this point. With a pourable material your build options are only limited to the thickness of your viewing panels right? Sorry I am getting ahead of myself - maybe let you guys answer first! LOL
Acrylic - no sweat on the PM, just wanted to shoot that over as a baseline to where I am coming from.
thanks again fellas!

 

[piiqmark]

Quote:
Originally Posted by 2Quills http:///t/196219/acrylic-bonding-techniques-aquarium-construction/60#post_3516042
I'd put a call in to some local shops and ask around about prices.
My guess is that it would be more expensive if all manufacturers built hex tanks by mitering all of the edges. Most of the cheaper/massed produced tanks are primarily heat formed and then have one vertical seam/joint. We see this a lot in acrylic bow fronts as well. More bending = less joining.
My plastics guy down here doesn't build tanks anymore. He said he used to but he stopped after people tried to take him to court twice for damages to their homes from tank failures. He said that fortunately he was able to prove in both cases that there was clear damage indicating the tanks were impacted in a fashion that caused them to fail but not because of poor craftsmanship. So he was fortunate.
Never the less he said he didn't want to deal with tank builds anymore because it wasn't worth it to him. But he told me that he believed the best method for building rectangular shaped tanks is to take a sheet of acrylic and cut each of the 4 corners of the sheet and then heat and fold it up like a box. So essentially you'd have no horizontal joints along the bottom of the tank at all...only the 4 vertical joints in the corners. And then the 4 sides along the top brace. I've never seen it done but he apparently swears by it.
The Problem is access to the same kinds of equipment that he uses in his shop.
Another thing that I've noticed when trying to form acrylic is how it deforms the edges of the piece where it is being formed or bent at. I need to try some different methods though for heating the material other than using a heat gun because it's easy to craze the material. I've seen a guy build is own bending bench for forming formica counter tops where electricity was used to supply the heat along a long metal shaft/tube. The table held the piece and then it had a top piece that folded down which supplied even pressure and force across the sheet I bet it wouldn't be to hard to build similar bender for the purose of using acrylic. I mean they're both plastics right?
There was also a voltage regulator used to control the amount of electrical current supplied in order to adjust the temperature of the heat shaft.
You said it - the reason i dont like the bending idea is how it deforms. It is U G L Y and unless you can hide it this is a focal point in your home and it will stick out like a sore thumb...
Forming with 4 verticals would be awesome but like you said the equiptment. Us DIY'ers might have a few more tools than the average garage and might be able to think out of the "tank" but where would you begin to make something like that. Maybe some kind of vacuum form? Even then we are talking about casting a mold, probably an oven or some kind of chemical - prices would (i imagine) be insane high to build just one.

 

[2quills]

Quote:
Originally Posted by piiqmark http:///t/196219/acrylic-bonding-techniques-aquarium-construction/60#post_3516066
So this guy sells a kit http://www.youtube.com/watch?v=ZkjsPrWT0Ic and this guy tells you how to use the wire he sells, this looks to be cheaper option (actually really cheap considering you could get a power supply for less than 100 bucks - 75 on amazon) http://www.youtube.com/watch?v=wVEf7PfuKxo I have also seen some instructionals where they take apart a hair dryer... no thanks on the hair dryer idea! LOL
Here is my issue with getting into something like this: in the second video towards the end he tells you thicker shets need a "V" groove cut prior to heating. While I am fine with that and capable of beading some weldon 40 up the the inside corner of the bend, Acrylic51 makes a great point earlier in this thread about the proper tools (specifically the router). The slightest bend in what should be a perfect straight line screws it up big time. Just like matching the corners on a sheet of paper and folding it. Once you fold it you can never go back to make it look perfect if you screw it up on the first shot. Paper is cheap acrylic, not so much! So this may work for some but I personally lack the confidence to tackle this.
Here is another question related to cutting, or should i say a way around it: If you think of a curved or bow shape, or even 2 45 angles to make a 90, you still have to cut base/floor pieces. Would it be possible to use some form of liquid acrylic or epoxy to form the floor of the tank? Would it bond to the acrylic and create enough strength and support assuming your stand/support structure is capable - think hardi-backer board you use in a bathroom over plywood. Is there such product? First thing that comes to mind is the bartop epoxy but is it thick enough, is it toxic when cured and will (if it does bond) create a strong enough bond to support what we are talking about? For the sake of conversation - lets say you could pour something in to create a bond. A tank of this size would probably never move and its likely in a home you own so construction/deconstruction isnt a problem at this point. With a pourable material your build options are only limited to the thickness of your viewing panels right? Sorry I am getting ahead of myself - maybe let you guys answer first! LOL
Exactly what I was getting at in my first post, a quality product isn't cheap. And folks will simply not do the work of a master builder their first shot out of the gate. My experience building tanks is pretty limited but I can tell you that it's worth it to start small and practice first. Pick up some cheap scraps from your local fab shop and play around a bit. Try building a perfect box.
If you bend the stuff you'd almost certainly have to cut again or and or plain/rout the edges back to weld ready condition.
From what I understand is that weld-on 40, 42 once mixed is essentially liquid acrylic. So it works like a solvent as well as a filler. If you purchased the components separately you could make it yourself. Theoretically you could probably mold the stuff if people aren't already. I'd be curious to know what it's structural properties would actually be.
Weld-on 3,4 are strictly liquid solvents that evaporate while the chemical and molecular changes are occuring. So when it's gone you can get left with air between your joints, bubbles, gaps, etc.
Weld-on 16 is solvent with some acrylic mixed in. So it does have some fill properties. But not as good as 40,42 have. And 16 doesn't have the strength that 40,42 have. Neither do 3,4.
Quote:
Originally Posted by piiqmark http:///t/196219/acrylic-bonding-techniques-aquarium-construction/60#post_3516067
You said it - the reason i dont like the bending idea is how it deforms. It is U G L Y and unless you can hide it this is a focal point in your home and it will stick out like a sore thumb...
Forming with 4 verticals would be awesome but like you said the equiptment. Us DIY'ers might have a few more tools than the average garage and might be able to think out of the "tank" but where would you begin to make something like that. Maybe some kind of vacuum form? Even then we are talking about casting a mold, probably an oven or some kind of chemical - prices would (i imagine) be insane high to build just one.
I peeked at a couple of hex tanks online last night. And it looks like most of them have 2 seams. Basically two halves of a tank that are joined together, each half has 2 bends. My guess is that they do miter the joints and then join them with something like 40,42 and then finish and polish them to make them look virtually seamless. That's what's supposed to be great about using 40,42...the ability to build the strongest and most seamlessly looking joints possible from what I understand.

 

[acrylic51]

Strength wise there isn't a ton of difference between 40&42 and 3&4......Equivalent unless annealing is done on the 40&42 solvent.......

 

[2quills]

Quote:
Originally Posted by acrylic51 http:///t/196219/acrylic-bonding-techniques-aquarium-construction/60#post_3516165
Strength wise there isn't a ton of difference between 40&42 and 3&4......Equivalent unless annealing is done on the 40&42 solvent.......
I dunno bud, I may have to defer to the manufacturers data sheets on this one.
According to IPS after 1 week of cure time weld on #3 has a strength rating of 2500 psi when cured at room temperature. Weld-on #40 after one week of cure time at room temp is rated for 4000 psi. Annealing at 120 degrees and 150 degrees you can achieve strengths of 5700 -7000 psi using the two part #40 and 42 product.. That coupled with the ability to create museum like quality joints sounds like a pretty significant difference to me. But I cannot confirm this myself.
http://www.tapplastics.com/uploads/pdf/PB-IPS3.pdf
http://www.curbellplastics.com/technical-resources/pdf/bond-acrylic-weldon-40.pdf

 

[acrylic51]

My info comes from probably the best in the business, because that was a question I raised to James.....Although I wouldn't take to much to what IPS says....They are dopes if you call them for help......

 

[acrylic51]

The annealing is the "key".....Where you gonna find an oven.......

 

[2quills]

Quote:
Originally Posted by acrylic51 http:///t/196219/acrylic-bonding-techniques-aquarium-construction/60#post_3516177
My info comes from probably the best in the business, because that was a question I raised to James.....Although I wouldn't take to much to what IPS says....They are dopes if you call them for help......
Tis why I question pretty much everyone and everything lol. I'm just presenting the information that the manufacturer is putting out there. I do remember some talk of James saying that there wasn't much difference between #3,4 and 16,...I think because 16 is really just 4 with essentially pieces of acrylic mixed in. Infact he says you can make your own 16 if you have some #3 or 4 by mixing some of your acrylic shavings in with it. But I thought he even had said that #40, 42 is the stronger product regardless if annealed. But who knows, I could be wrong. This is why believe it is good to have healthy discussion in order to gain other perspectives and experiences in an effort to make smarter choices.