Weldon 16 seams

ReefKeeperNYC · 01/08/2018, 04:50 PM

So I built my tank.

I felt that maybe i underbuilt it for the size.

I cut it in half and put a new side panel and now feel more at ease.

I have a question.

I use weldon 3 initially, I used weldon 4 for that one panel and i used weldon 16 like a “silicon” along the tank seams.

I figured i would research that and found a thread where the user bean animal, mentions that, that causes stress.

Now im feeling more stress 😂😂😂

I used 1/4” acrylic, tank is 32 x 18 x 12 now.

Is this god telling me to stop? Lol

Or am i good to go?

It “seamed” like a good idea.

Did i mess up again?

OzIA · 01/08/2018, 05:28 PM

12 inches deep? Any bracing (euro bracing, etc) along the top?

ReefKeeperNYC · 01/08/2018, 05:33 PM

Quote:

Originally Posted by OzIA

12 inches deep? Any bracing (euro bracing, etc) along the top?

Yes 4” bracing around. Strips not euro. I regret that too

ReefKeeperNYC · 01/08/2018, 05:33 PM

And yes 12” deep. But water line will be about 10”

OzIA · 01/08/2018, 05:45 PM

It may bow a little but will probably hold if you have good seams. If I did my math correctly, that about 90 pounds of pressure agains the long walls (average). Roughly 30 gallons at 12 inches so drop that and the amount pressures will fall as well.

Acrylic that size will warp on it's own just by getting wet.

ReefKeeperNYC · 01/08/2018, 05:49 PM

Quote:

Originally Posted by OzIA

It may bow a little but will probably hold if you have good seams. If I did my math correctly, that about 90 pounds of pressure agains the long walls (average). Roughly 30 gallons at 12 inches so drop that and the amount pressures will fall as well.

Acrylic that size will warp on it's own just by getting wet.

Would you trust it?

at a 10" water level?

OzIA · 01/08/2018, 05:54 PM

At 10 inches that puts you at around 65 lbs of pressure on the long walls. I guess it depends on the seams? Are they clear (no bubbles). The 16 will help some. Is this a display tank?

tkeracer619 · 01/08/2018, 06:13 PM

I think you worry too much and should buy tanks from reputable builders from now on if you hope to have any sleep while in this hobby. Not trying to be rude, just trying to keep it real.

Water on the floor is a real concern. It's the thing of nightmares when you run a maintenance business.

hijinks · 01/08/2018, 06:22 PM

The way you put 16 down it will only help if one of the seams has a leak. It won't help the strength that much at all

ReefKeeperNYC · 01/08/2018, 08:20 PM

Quote:

Originally Posted by OzIA

At 10 inches that puts you at around 65 lbs of pressure on the long walls. I guess it depends on the seams? Are they clear (no bubbles). The 16 will help some. Is this a display tank?

Seams are clear. a few areas of micro bubbles. which i reinforced with a iece of acrylic at the edge.

Display tank yes. its in my bedroom.

ReefKeeperNYC · 01/08/2018, 08:21 PM

Quote:

Originally Posted by tkeracer619

I think you worry too much and should buy tanks from reputable builders from now on if you hope to have any sleep while in this hobby. Not trying to be rude, just trying to keep it real.

Water on the floor is a real concern. It's the thing of nightmares when you run a maintenance business.

Oh trust me, this will be my last DIY Acrylic build.

not taken as rude, i would rather you keep it real.

I dont want to have to deal with water in my room. hence my fear.

der_wille_zur_macht · 01/08/2018, 10:00 PM

Weldon 16 in a fillet is usually not a good idea. It doesn't really solve the problem and it can cause additional problems. People do it in the hopes that it will fill gaps in bad seams or act like a reinforcement. It can fill gaps, but a gap filled with weldon 16 will be a pretty weak seam even though it's filled, and a fillet made from 16 isn't really adding any strength.

The concern is that the solvent in the cement is going to stress the material around the seam. This material has already been stressed three times (saw cut, routered flat, solvent welded). It's already delicate and now you're adding gas to the fire. "Stressed" acrylic basically means the chemical bonds between the molecules are starting to break down. This weakens the material significantly. Sometimes, the effect is so bad that fine hairlines appear on the surface of the material - these surface cracks are called crazing, and it happens as the bonds in the material start to break down.

I hate to say this and I don't mean to sound snotty, but the "best" thing to do is build it right the first time. Acrylic can't be worked over and over and tweaked and patched and fiddled with like some materials. It's more or less a one and done material, if you care about ultimate strength. If you don't get a seam right the first time, the material is basically scrap. You can break the seam and machine the piece smaller but it's not easy to repair a bad seam without actually making it worse. Although I suppose it depends on why the seam was considered bad in the first place.

ReefKeeperNYC · 01/08/2018, 10:13 PM

Quote:

Originally Posted by der_wille_zur_macht

Weldon 16 in a fillet is usually not a good idea. It doesn't really solve the problem and it can cause additional problems. People do it in the hopes that it will fill gaps in bad seams or act like a reinforcement. It can fill gaps, but a gap filled with weldon 16 will be a pretty weak seam even though it's filled, and a fillet made from 16 isn't really adding any strength.

The concern is that the solvent in the cement is going to stress the material around the seam. This material has already been stressed three times (saw cut, routered flat, solvent welded). It's already delicate and now you're adding gas to the fire. "Stressed" acrylic basically means the chemical bonds between the molecules are starting to break down. This weakens the material significantly. Sometimes, the effect is so bad that fine hairlines appear on the surface of the material - these surface cracks are called crazing, and it happens as the bonds in the material start to break down.

I hate to say this and I don't mean to sound snotty, but the "best" thing to do is build it right the first time. Acrylic can't be worked over and over and tweaked and patched and fiddled with like some materials. It's more or less a one and done material, if you care about ultimate strength. If you don't get a seam right the first time, the material is basically scrap. You can break the seam and machine the piece smaller but it's not easy to repair a bad seam without actually making it worse. Although I suppose it depends on why the seam was considered bad in the first place.

The welds were actually really good. only a few areas where there were bubbles. but pretty much clear welds all around.

I thought I could have used it as a "sealant". I didnt know about the stress on the edges and such.

Then i was googling weldon 16 threads and found info i wasnt aware of.

I will leak test it for wayy longer than typical and do it slooowwww.

This is my first diy acrylic tank, so it goes without saying, there is a lot I have learned! I thought I researched all i can, but physical implementation and application is better learning experience than just reading.

I appreciate it, and will do better next time!

ReefKeeperNYC · 01/08/2018, 10:14 PM

*if there is a next time =P

ReefKeeperNYC · 01/09/2018, 12:00 PM

Just one last question. Before i possibly exacerbate the situation.

If i put some 3/8 strips along the seams and use weldon4 would that reinforce the seams? Or since i put the 16 theres no going back?

I was thinking of lightly sanding the seam edges to clear off the 16 and putting the braces indide the seams on the front and back bottom and vertical seams. I need this tank to be as close to bulletproof as possible...

OzIA · 01/09/2018, 02:38 PM

I've used that method to repair failed seams but never on top of 16. I'd say that once you used the 16, even if you sanded it off, there would be gaps. 4 probably wouldn't work. You would probably have to use 16 on the 3/8 strips.

OzIA · 01/09/2018, 02:42 PM

Oh yeah, and it's not going to look very good. If this were a sump, no big deal.

ReefKeeperNYC · 01/09/2018, 03:10 PM

Quote:

Originally Posted by OzIA

I've used that method to repair failed seams but never on top of 16. I'd say that once you used the 16, even if you sanded it off, there would be gaps. 4 probably wouldn't work. You would probably have to use 16 on the 3/8 strips.

I only have 4 left.

Yea. I think this tank is botched...

I should have done the strips first instead of the 16... but what did I know..

Thanks for the help! Ill still look at it positively as a learning experience.

OzIA · 01/09/2018, 05:18 PM

I've got plenty of failed projects in my bone yard too. I wouldn't throw it away unless you just don't have the space. I usually find a use for some part of later.

ReefKeeperNYC · 01/09/2018, 05:33 PM

Quote:

Originally Posted by OzIA

I've got plenty of failed projects in my bone yard too. I wouldn't throw it away unless you just don't have the space. I usually find a use for some part of later.

Good idea. Maybe itll be a sump for a future tank build 🤪🤪🙏🏼🙏🏼

der_wille_zur_macht · 01/09/2018, 07:33 PM

Quote:

Originally Posted by ReefKeeperNYC

The welds were actually really good. only a few areas where there were bubbles. but pretty much clear welds all around.

I thought I could have used it as a "sealant". I didnt know about the stress on the edges and such.

Then i was googling weldon 16 threads and found info i wasnt aware of.

I will leak test it for wayy longer than typical and do it slooowwww.

This is my first diy acrylic tank, so it goes without saying, there is a lot I have learned! I thought I researched all i can, but physical implementation and application is better learning experience than just reading.

I appreciate it, and will do better next time!

A good leak test is great, but many "bad" acrylic seams will hold water for at least a few days/weeks/months/sometimes years. Acrylic that's been weakened by stress will usually not fail immediately, it'll just slowly get worse under pressure until the seam comes apart. I'd say it's probably just as common for a bad tank to fail after some time as it is for it to fail an initial leak test.

If your welds were good to begin with, then you didn't need ANY reinforcement - weldon 16 or acrylic stock glued in the corners. Again, I don't want to come across as harsh here, but you really just need to get it right the first time, and not worry about reinforcements. Partially this is true because of stress introduced by reinforcements (ie weldon 16) but it's also true just as a matter of practice - if you're "bad" at making the seam to begin with, you'll probably do a bad job of the repair/reinforcement, and it probably won't help. If you had bad seams because they weren't machined flat, you probably won't machine the reinforcement flat, and it won't work. If you had bad seams because you were sloppy with the solvent, you'll probably be sloppy again - you get the picture. Practice, practice, practice on scrap. Watch videos. Be mindful of who and where you get advice from though, as there are a lot of "reputable" sources in the aquarium hobby world who are giving out horrible advice (ie that king of DIY guy on youtube).

Acrylic seams need to be cut accurately, machined flat, then solvent welded with good technique. If you get it wrong, the only real option is to cut and machine the parts slightly smaller and save the stock for something else (or machine and build your original project an inch or two smaller in every dimension). For me at least, that's it. Yes, there can be repairs that hold, but you're on risky ground.

der_wille_zur_macht · 01/09/2018, 07:40 PM

Let me just add that I would not consider myself an expert at acrylic and I am speaking as much from experience failing as getting it right!

lapin · 01/10/2018, 08:02 AM

Before you decide the sky is falling with out seeing any of it come down, may I make a suggestion. Put some water in it and see how it goes. Maybe in your garage on a piece of plywood. In a bath tub on 2x4's and plywood over them. If you don't try, you fail without knowing if you failed. I have crashed and burned a few times and other times things came out great. Go for it..............

ReefKeeperNYC · 01/10/2018, 02:25 PM

Quote:

Originally Posted by lapin

Before you decide the sky is falling with out seeing any of it come down, may I make a suggestion. Put some water in it and see how it goes. Maybe in your garage on a piece of plywood. In a bath tub on 2x4's and plywood over them. If you don't try, you fail without knowing if you failed. I have crashed and burned a few times and other times things came out great. Go for it..............

thank you for your suggestion. I will give the strips a try. And do an extended leak test

I calculated that there will be roughly only 7.5-8 inches of water after sand bed and 2 inches from tank top water line.

Thats about 20-25 gallons. 32” x 18 x 12” high

My 20 high has 3/16 walls glass. So i guess at 1/4 acrylic with top bracing and 3/8 reinforcement at seam, cant be any weaker than my 20gal high?

Youre right im just spooked since im diving into new water with acrylic.

Grazie

Acrylics · 01/12/2018, 01:35 PM

Quote:

Originally Posted by ReefKeeperNYC

Just one last question. Before i possibly exacerbate the situation.

If i put some 3/8 strips along the seams and use weldon4 would that reinforce the seams? Or since i put the 16 theres no going back?

I was thinking of lightly sanding the seam edges to clear off the 16 and putting the braces indide the seams on the front and back bottom and vertical seams. I need this tank to be as close to bulletproof as possible...

Weldo-on 16 is basically the same as 4 but with some acrylic monomer thrown in as a "thickener" of sorts to make it more syrupy. The secondary application of 4 is akin to adding the 16 to start with. And yeah, once you have that layer of goop on there from the 16 - you pretty much *can't* add the strips anyway.

Sanding the 16 parts off doesn't change the fact that the molecular chains have been further stressed by the 16.

It really is all bout the added stress and you really don't gain anything from the addition of 16. I wouldn't say you *will* have problems with your tank as-is, just take a look around the affected areas and look for little fractures starting from the fillet of 16 and base your decisions accordingly. If you don't have any little stress fractures (crazing) then you should be good to go for the leak test

If you do, it'd probably be best to simply do a re-build with some lessons learned and keep the old one for a sump or some other application

HTH,
James

01/08/2018, 04:50 PM	#1
ReefKeeperNYC Registered Member Join Date: Dec 2017 Location: New York City Posts: 84	Weldon 16 seams So I built my tank. I felt that maybe i underbuilt it for the size. I cut it in half and put a new side panel and now feel more at ease. I have a question. I use weldon 3 initially, I used weldon 4 for that one panel and i used weldon 16 like a “silicon” along the tank seams. I figured i would research that and found a thread where the user bean animal, mentions that, that causes stress. Now im feeling more stress 😂😂😂 I used 1/4” acrylic, tank is 32 x 18 x 12 now. Is this god telling me to stop? Lol Or am i good to go? It “seamed” like a good idea. Did i mess up again?

01/08/2018, 06:13 PM	#8
tkeracer619 Registered Member Join Date: Jan 2006 Location: Westminster, CO Posts: 17,289	I think you worry too much and should buy tanks from reputable builders from now on if you hope to have any sleep while in this hobby. Not trying to be rude, just trying to keep it real. Water on the floor is a real concern. It's the thing of nightmares when you run a maintenance business. __________________ Hobby Experience: 9200ish gallons, 26 skimmers, and a handful of Kent Scrapers. Current Tank: Vortech Powered 600G SPS Tank w/ 100gal frag tank & 100g Sump. RK2-RK10 Skimmer. ReefAngel. Radium 20k.

01/08/2018, 10:00 PM	#12
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	Weldon 16 in a fillet is usually not a good idea. It doesn't really solve the problem and it can cause additional problems. People do it in the hopes that it will fill gaps in bad seams or act like a reinforcement. It can fill gaps, but a gap filled with weldon 16 will be a pretty weak seam even though it's filled, and a fillet made from 16 isn't really adding any strength. The concern is that the solvent in the cement is going to stress the material around the seam. This material has already been stressed three times (saw cut, routered flat, solvent welded). It's already delicate and now you're adding gas to the fire. "Stressed" acrylic basically means the chemical bonds between the molecules are starting to break down. This weakens the material significantly. Sometimes, the effect is so bad that fine hairlines appear on the surface of the material - these surface cracks are called crazing, and it happens as the bonds in the material start to break down. I hate to say this and I don't mean to sound snotty, but the "best" thing to do is build it right the first time. Acrylic can't be worked over and over and tweaked and patched and fiddled with like some materials. It's more or less a one and done material, if you care about ultimate strength. If you don't get a seam right the first time, the material is basically scrap. You can break the seam and machine the piece smaller but it's not easy to repair a bad seam without actually making it worse. Although I suppose it depends on why the seam was considered bad in the first place. __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman)

01/09/2018, 07:40 PM	#22
der_wille_zur_macht Team RC Member Join Date: Sep 2003 Location: NY Posts: 17,749	Let me just add that I would not consider myself an expert at acrylic and I am speaking as much from experience failing as getting it right! __________________ Inconveniencing marine life since 1992 "It is my personal belief that reef aquaria should be thriving communities of biodiversity, representative of their wild counterparts, and not merely collections of pretty specimens growing on tidy clean rock shelves covered in purple coralline algae." (Eric Borneman)

01/08/2018, 05:28 PM	#2
OzIA Registered Member Join Date: Sep 2016 Posts: 214	12 inches deep? Any bracing (euro bracing, etc) along the top?

01/08/2018, 05:33 PM	#4
ReefKeeperNYC Registered Member Join Date: Dec 2017 Location: New York City Posts: 84	And yes 12” deep. But water line will be about 10”

01/08/2018, 05:45 PM	#5
OzIA Registered Member Join Date: Sep 2016 Posts: 214	It may bow a little but will probably hold if you have good seams. If I did my math correctly, that about 90 pounds of pressure agains the long walls (average). Roughly 30 gallons at 12 inches so drop that and the amount pressures will fall as well. Acrylic that size will warp on it's own just by getting wet.

01/08/2018, 05:54 PM	#7
OzIA Registered Member Join Date: Sep 2016 Posts: 214	At 10 inches that puts you at around 65 lbs of pressure on the long walls. I guess it depends on the seams? Are they clear (no bubbles). The 16 will help some. Is this a display tank?

01/08/2018, 06:22 PM	#9
hijinks Registered Member Join Date: Dec 2008 Location: Colorado Posts: 505	The way you put 16 down it will only help if one of the seams has a leak. It won't help the strength that much at all

01/08/2018, 10:14 PM	#14
ReefKeeperNYC Registered Member Join Date: Dec 2017 Location: New York City Posts: 84	*if there is a next time =P

01/09/2018, 12:00 PM	#15
ReefKeeperNYC Registered Member Join Date: Dec 2017 Location: New York City Posts: 84	Just one last question. Before i possibly exacerbate the situation. If i put some 3/8 strips along the seams and use weldon4 would that reinforce the seams? Or since i put the 16 theres no going back? I was thinking of lightly sanding the seam edges to clear off the 16 and putting the braces indide the seams on the front and back bottom and vertical seams. I need this tank to be as close to bulletproof as possible...

01/09/2018, 02:38 PM	#16
OzIA Registered Member Join Date: Sep 2016 Posts: 214	I've used that method to repair failed seams but never on top of 16. I'd say that once you used the 16, even if you sanded it off, there would be gaps. 4 probably wouldn't work. You would probably have to use 16 on the 3/8 strips.

01/09/2018, 02:42 PM	#17
OzIA Registered Member Join Date: Sep 2016 Posts: 214	Oh yeah, and it's not going to look very good. If this were a sump, no big deal.

01/09/2018, 05:18 PM	#19
OzIA Registered Member Join Date: Sep 2016 Posts: 214	I've got plenty of failed projects in my bone yard too. I wouldn't throw it away unless you just don't have the space. I usually find a use for some part of later.

01/10/2018, 08:02 AM	#23
lapin Registered Member Join Date: Aug 2017 Location: Austin Posts: 801	Before you decide the sky is falling with out seeing any of it come down, may I make a suggestion. Put some water in it and see how it goes. Maybe in your garage on a piece of plywood. In a bath tub on 2x4's and plywood over them. If you don't try, you fail without knowing if you failed. I have crashed and burned a few times and other times things came out great. Go for it..............