Acrylic fabrication questions? I can help!

[Floyd R Turbo]

Hello all,

I have just started reading this thread from way, way back in the archives. Forgive me please for asking questions that I'm sure have been repeated again and again. But I'm working on a project and would like to get started this weekend, so I'll be ordering supplies now and reading up.

So I currently have Weld-On 3, 16, 2007 (for PVC) and 40, a 10" table saw w/diablo plastic cutting blade, a router with an acrylic cutting bit (but not a flush trim bit, which I need) and a varying supply of clear and black acrylic.

So right now I'm going to be building a filter enclosure that will hold a small amount of water, but eventually will want to start building frag tanks, sumps, and possibly tanks. To start, I'm going to just get my feet wet with the less complicated builds.

Up until now, I've been using Weld-on #3 which works fine. But I have started to notice on my filter box that the joint is not 100% bubble free and is starting to peel at the top. I know why now, I need to be using the pins method and WO #4, and also oversizing the sheet so that I get a fillet joint and then flush trim and polish to get the bubble free joint, and let it sit without water contact for at least a week, maybe 2 (since it's not a pressurized application, I figure a week is sufficient).

My question is related to cast vs extruded. Specifically, opaque to clear bonding.

I understand that the preferred materials are Polycast, Acrylite GP, and Plexiglas G (thank you Acrylics) and domestic always for tanks. These filter enclosures are typically 24" long, 9" tall, and 3" wide and externally braced to prevent bowing and provide protection for light fixtures mounted to the side. This is for an Algae Scrubber. There will be a mix of clear and black acrylic. From what I understand, clear acrylic is extruded until you get to 1/4" thick, 1/4" can be either extruded or cast, then generally anything larger is cast. At least that' what my local shop carries. So my choice at this point is to use 1/4", but if it's so small, does it matter if I choose cast or extruded?

Also, is it correct that all opaque/colored acrylic (be it black, white, red, green, etc) is going to be extruded? Does that mean that for a watertight application, you have to go a size larger when using opaque, or is there another rule of thumb?

I see a lot of tanks with a blue back, I guess I haven't looked close, but I suppose that piece could just be inside the tank and laminated to the back, so that it's not structural, it just forms the overflow.

The box I want to build will have clear sides to let light through, and black all around the rest, bottom, sides, external braces, etc. So is there anything that I should know when trying to bond a piece of clear 1/4" (cast or extruded) to a piece of black 1/4"? Does it make a difference which one is butted up against the other?

Also I read early on in this thread that WO #4 and pins method gives you the strongest bubble free joints. I also read that in warmer temperatures (during an Iowa summer, in the garage for instance) that mixing in 20% WO #5 will increase the working time and allow for a better bond strength. IPS just merged with some company called SciGrip and now all the data sheets are in different spots and I can't find the one on WO #5, but I found it online. It doesn't seem common, so I was wondering if this step is necessary, if WO #5 has been replaced with another product or number, or what.

I look forward to reading the rest of this thread and starting my acrylic building career ASAP!

 

[Floyd R Turbo]

One more thing I forgot about. Needles/syringes. For applying the WO #3, I've got a couple squeeze bottles and several needles, I don't know for sure what I have but it looks like the Hypo 23 or 25, I think I have both, a few more of the larger ones. They work well for WO #3, I'm assuming those are the same I should use for WO #4?

 

[Acrylics]

So I currently have Weld-On 3, 16, 2007 (for PVC) and 40,

not sure why you'd need the 2007, just use PVC pipe cement for that. 2007 is just THF - the primary active in PVC pipe cement. It is a very volatile solvent so generally evaporates before a really good bond can be achieved. The resin added to PVC pipe cement gives a longer working time, but not *that* much longer

Up until now, I've been using Weld-on #3 which works fine. But I have started to notice on my filter box that the joint is not 100% bubble free and is starting to peel at the top. I know why now, I need to be using the pins method and WO #4, and also oversizing the sheet so that I get a fillet joint and then flush trim and polish to get the bubble free joint, and let it sit without water contact for at least a week, maybe 2 (since it's not a pressurized application, I figure a week is sufficient).

don't worry about polishing. It doesn't help anything other than looking cute, concentrate on technique first, and then polish only when necessary

My question is related to cast vs extruded. Specifically, opaque to clear bonding.

I understand that the preferred materials are Polycast, Acrylite GP, and Plexiglas G (thank you Acrylics) and domestic always for tanks. These filter enclosures are typically 24" long, 9" tall, and 3" wide and externally braced to prevent bowing and provide protection for light fixtures mounted to the side. This is for an Algae Scrubber. There will be a mix of clear and black acrylic. From what I understand, clear acrylic is extruded until you get to 1/4" thick, 1/4" can be either extruded or cast, then generally anything larger is cast. At least that' what my local shop carries. So my choice at this point is to use 1/4", but if it's so small, does it matter if I choose cast or extruded?

Both extruded and cast are available at any thickness below 1" and in virtually any color. For small stuff like this - no, it really doesn't matter. I'd much rather see you use a good extruded like Acrylite FF than a bad cast.

Also, is it correct that all opaque/colored acrylic (be it black, white, red, green, etc) is going to be extruded? Does that mean that for a watertight application, you have to go a size larger when using opaque, or is there another rule of thumb?

colored acrylic is available in cast and extruded in any thickness 1/2" and thinner. After that - it's usually cast and definitely cast for anything 1" or above.

I see a lot of tanks with a blue back, I guess I haven't looked close, but I suppose that piece could just be inside the tank and laminated to the back, so that it's not structural, it just forms the overflow.

you can if you wish, but I wouldn't recommend it. Just get the proper thickness of whatever color you want.

The box I want to build will have clear sides to let light through, and black all around the rest, bottom, sides, external braces, etc. So is there anything that I should know when trying to bond a piece of clear 1/4" (cast or extruded) to a piece of black 1/4"? Does it make a difference which one is butted up against the other?

nope, makes no difference at all. But I do like to glue clear onto the black so I can see the joint as I'm gluing

Also I read early on in this thread that WO #4 and pins method gives you the strongest bubble free joints. I also read that in warmer temperatures (during an Iowa summer, in the garage for instance) that mixing in 20% WO #5 will increase the working time and allow for a better bond strength. IPS just merged with some company called SciGrip and now all the data sheets are in different spots and I can't find the one on WO #5, but I found it online. It doesn't seem common, so I was wondering if this step is necessary, if WO #5 has been replaced with another product or number, or what.

Actually, stronger bonds can be made from straight MC but it's hard to work with at times as it doesn't flow evenly and is *super* fast.
WO 5 was discontinued a coupla years ago, and I wouldn't trust any old stock you can find. Just make your own or buy MCBond from polysciences. WO5 was just MC and acetic acid, no magic to it

Needles/syringes. For applying the WO #3, I've got a couple squeeze bottles and several needles, I don't know for sure what I have but it looks like the Hypo 23 or 25, I think I have both, a few more of the larger ones. They work well for WO #3, I'm assuming those are the same I should use for WO #4?

yup, they'll work fine If you ever get into thicker materials or get real comfy, you can use the larger ones for solvent as well. I won't go back to the smaller ones ever again - not worth the time

HTH,
James

 

[Floyd R Turbo]

Thanks James, great info.

I don't plan on using any inferior products. My local shop carries Acrylite and Plexiglas, so I figure that I can't go wrong for the boxes I'm building for now. I will just have to pay attention when I start making more complicated builds.

But if I understand correctly,

1) Spartech Polycast
2) Evonik Cyro Acrylite GP
3) Plexiglas G

Would be the top 3 cell cast brands to use, in that order of preference. Correct? Would any of these fall into the "bad cast" category? Or am I going to be fine with any of these?

As for the MC, I found their site, that's stuff is expensive. I already have the WO #4 on the way, so I should be fine with what I am building for now I think. But good to know there is something better in case I run into issues with WO.

What is the rationale behind the preference of MC over WO? When you say it's "really fast" do you mean that it forms the bond faster, or that it's thinner / moves faster? I thought the rationale behind using #4 over #3 was that the initial working time is longer, which allows more melting of each side to form a stronger bond. Where does MC fall in relation to all of that?

 

[Acrylics]

But if I understand correctly,

1) Spartech Polycast
2) Evonik Cyro Acrylite GP
3) Plexiglas G

Would be the top 3 cell cast brands to use, in that order of preference. Correct? Would any of these fall into the "bad cast" category? Or am I going to be fine with any of these?

Correct, and you'll be fine with any of these

As for the MC, I found their site, that's stuff is expensive. I already have the WO #4 on the way, so I should be fine with what I am building for now I think. But good to know there is something better in case I run into issues with WO.

IMO you'd be better served by making your own by simply buying the ingredients at at lab supply store. You'd be able to make it cheaper, in smaller quantities, and customized to your application. That said, MCBond is still good stuff

What is the rationale behind the preference of MC over WO? When you say it's "really fast" do you mean that it forms the bond faster, or that it's thinner / moves faster? I thought the rationale behind using #4 over #3 was that the initial working time is longer, which allows more melting of each side to form a stronger bond. Where does MC fall in relation to all of that?

Straight methylene chloride forms the bonds faster. The viscosity of all sovents is about equivalent. WO 16 is not something I even consider.. period

IPS (mfrs of WO) put a bunch of garbage in their solvents, for a coupla reasons:
*Orange County OSHA type laws (VOCs, etc) many of the big fabricating companies are in Orange Couty..
*to make the solvents more suitable for other plastics as well. Broadening the ability of the solvent, but it doesn't make the solvent any better *for acrylic*. In essence, the solvent is a jack of all trades, master of none.

Throughout the last ~15 years, IPS has (IMO) really screwed up their solvents, probably for good reason (OSHA, etc) but the solvents have gone down considerably in quality, again, in my personal opinion.

Not accounting for the worthless amount of monomer in the solvents.. 20 years ago, WO 3 was straight methylene chloride, WO 4 was methylene chloride & ethylene dichloride (dichlorethane,) and WO 5 was methylene chloride and acetic acid.. all were good. Look at the ingredients now

MCBond, from Polysciences, has used the same solvent for at least the last 20-25 years and it works well. It is roughly equivalent to the old WO 5. MCBond is methylene chloride and acetic acid. The acid will slow the reaction down and help the solvent flow better into the joint.

The only chemical in any of the WO solvents that actually does anything useful is methylene chloride, everything else is for the most part - utterly useless. Where solvent bonding is concerned, we'd rather have straight methylene chloride as it will produce the strongest bonds, without question. But, it is very fast. If you were to glue the bottom of a 125g tank, you start at one corner and circle around the tank. If you were to do this using straight methylene chloride, the joint would already be set before the joint was completed.. and this can be bad news.

Contrary to popular belief, long soak times are not wanted if you want optimum joint strength. Given equal materials, the longer working time is to allow you to pull wires, shim where necessary, and still get a clean looking joint. Cast acrylic has much longer molecular chains (mole wt) than extruded does so needs a bit more time to break those down and get a clean looking joint, but not nearly the 2 minutes that some like. For a thickness like 1/2" - 15-30 seconds is more than adequate. For my museum cases, 15 seconds is plenty and produces bubble-free joints that you simply cannot break.

HTH,
James

 

[Floyd R Turbo]

Wow, I had not even considered making my own. Being an engineer (not chemical, but what does it really matter 15 years out of college) I guess I will start searching for a local lab supply store.

If MC Bond is just methylene chloride and acetic acid, what would the mixture percentages be? Would I need to obtain a lab grade acetic acid, or are we talking straight white vinegar from the grocery store (in a glass bottle)? Any precautions, like what to add to what, mixing technique, storage bottles, etc? I can probably get those ?'s answered at the lab supply but since I'm here...

So if WO 4 isn't ideal, I assume it's not complete junk either? I guess at this point I'm trying to justify the $13 I just spent for a jar of it!!! I've been using WO 3 up until now and it's worked. Always a good idea to learn how to use the right stuff early though, so I will being my search for DIY...

 

[Floyd R Turbo]

I found this for MC and Acetic, just want to double check that this is what I am looking for. No luck so far finding a local supplier, but not finished looking.

http://www.coleparmer.com/catalog/product_view.asp?referred_id=1965&sku=8910013
http://www.coleparmer.com/catalog/product_view.asp?referred_id=1965&sku=8900001

 

[Acrylics]

the MC is fine, but I don't see an assay for the acid in the MSDS. Verify that it's 99+% and you're good to go

James

 

[blackizzz]

James, what thickness acrylic would a 48x24x20" require?
How thick eurobrace? Would a crossbrace be required?

Thanks!!!

Oskar

 

[madmike]

Quote:
Quick question for you James, I used weld-on 4 for the first time in awhile (ran out of your recipe) and I had a problem. The solvent went into the joint just fine... pulled the pins in about 30 seconds or so and left it to dry. When I returned, it looked as though only the middle of the joint (1/2" material) had a nice melt. Both the outside and the inside looked like all of the solvent evaperated and left a very poor looking joint. I am thinking I pulled the pins too soon before the material had a chance to really melt and didn't form any sort of a dam of melted acrylic to keep the solvent in the joint. Does that sound right/make sense? Do you think something else could have happened?

Try pulling the pins sooner actually, I'm not a big fan of soaking the joint as long as some others are
..and yeah, mine's made for a specific material at a specific temperature, blah blah..

Thanks for the info, I think I will try to make my own. Is your recipe for solvent just pure methylene chloride with glacial acetic acid? What percent of each? You can PM me if you don't want the info public.

 

[Floyd R Turbo]

the MC is fine, but I don't see an assay for the acid in the MSDS. Verify that it's 99+% and you're good to go

James

After calling many places, I found out that my local acrylic supplier uses straight MC from Craftics and I can buy that from them. They also use Acetic Acid but said I could not buy that from them. They told me who they buy it from (Omaha, 2+ hrs away), and I found out that it the "Glacial" Acetic Acid is the ultra-pure stuff. There is something called "80% certified" and "97% uncertified" and "Glacial" sold by Cole-Parmer, but it's like $20 hazmat per bottle on top of shipping, same for the AA so that's ridiculous. The Omaha place had a good price for 2.5 L of AA & have relatives there that could pick it up.

So what is the mixture rate of MC to AA (by weight, by volume, maximum mixture, etc)? And how much extra working time does that give per amount mixed in?

 

[gods child]

Acrylics ,sir are you from long island?

 

[Floyd R Turbo]

Well I just pulled up the MSDS on Polysciences' site. I didn't recall that there was a 3rd ingredient. But I see now that the CAS #'s are listed as well as the ratios of mixing. So when you said you're better off to make your own MC bond I guess I should have looked a little closer at their site! Now I need to search for Methyl Methacrylate also!

MC Bond's mix is:

5% Acetic Acid
13.75% Methyl Methacrylate
81.25% Methylene Chloride

Now my local place just uses MC and AA, but they don't make tanks. I could probably get away with that for the filter boxes I'm making. Sounds like I'd be better off then I would be using WO #3 or #4 anyways. So now to search for MM.

 

[Acrylics]

James, what thickness acrylic would a 48x24x20" require?
How thick eurobrace? Would a crossbrace be required?

3/8" minimum, 1/2" is preferable. 3" eurobrace and 6" centerbrace. If you wanted to go 3/4" or better, then you can get rid of the crossbracing.

Thanks for the info, I think I will try to make my own. Is your recipe for solvent just pure methylene chloride with glacial acetic acid? What percent of each? You can PM me if you don't want the info public.

no, I add ethylene dichloride, but at $200+/gallon and not readily available - not something I spec out too much. Even lab supply shops don't keep it in stock as it's *very* hazardous.

After calling many places, I found out that my local acrylic supplier uses straight MC from Craftics and I can buy that from them. They also use Acetic Acid but said I could not buy that from them. They told me who they buy it from (Omaha, 2+ hrs away), and I found out that it the "Glacial" Acetic Acid is the ultra-pure stuff. There is something called "80% certified" and "97% uncertified" and "Glacial" sold by Cole-Parmer, but it's like $20 hazmat per bottle on top of shipping, same for the AA so that's ridiculous. The Omaha place had a good price for 2.5 L of AA & have relatives there that could pick it up.

So what is the mixture rate of MC to AA (by weight, by volume, maximum mixture, etc)? And how much extra working time does that give per amount mixed in?

I'd start at 5% acid solution by volume, and go from there. Working time depends on too many things; temperature, mole wt of the material, humidity, etc. so can't be precise on this. But never exceed 10% acid.

80% is no good, too much water in it and that will ruin your joints, this is normally sold as "photo grade" for the acid wash in developing
97% *might* be okay, but wouldn't recommend it.

Acrylics ,sir are you from long island?

no, about 3000 miles west of there

Well I just pulled up the MSDS on Polysciences' site. I didn't recall that there was a 3rd ingredient. But I see now that the CAS #'s are listed as well as the ratios of mixing. So when you said you're better off to make your own MC bond I guess I should have looked a little closer at their site! Now I need to search for Methyl Methacrylate also!

MC Bond's mix is:

5% Acetic Acid
13.75% Methyl Methacrylate
81.25% Methylene Chloride

Now my local place just uses MC and AA, but they don't make tanks. I could probably get away with that for the filter boxes I'm making. Sounds like I'd be better off then I would be using WO #3 or #4 anyways. So now to search for MM.

Don't worry about it, it's meaningless and absolutely worthless. Methyl methacrylate is unpolymerized acrylic resin. Something I would never add to a solvent.

James

 

[Floyd R Turbo]

no, I add ethylene dichloride, but at $200+/gallon and not readily available - not something I spec out too much. Even lab supply shops don't keep it in stock as it's *very* hazardous.

Just out of sheer curiosity, what benefit for this ingredient add?

I'd start at 5% acid solution by volume, and go from there. Working time depends on too many things; temperature, mole wt of the material, humidity, etc. so can't be precise on this. But never exceed 10% acid.

Perfect. Thanks!!!

80% is no good, too much water in it and that will ruin your joints, this is normally sold as "photo grade" for the acid wash in developing
97% *might* be okay, but wouldn't recommend it.

Yeah my local place uses Glacial and that's actually ACS grade (American Chemical Society) which is the top grade

Don't worry about it, it's meaningless and absolutely worthless. Methyl methacrylate is unpolymerized acrylic resin. Something I would never add to a solvent.

James

Very good to know. I wonder why MC Bond has it then?

Well I called Craftics and they couldn't tell me what grade of MC they used, they said they would call their supplier and get back to me. I called Polysciences and they told me that their ingredients are all Tech grade, which is actually the lowest grade you can get. Then again the person I talked to may not have known what she was talking about.

The place I found where my Dad lives have Lab grade and they told me "anything is better than tech grade".

The grades go:

Tech - industrial
Purified - educational
Lab - educational
S
USP - food/drug/medical
Reagent
ACS - highest grade

Acrylics, what grade of MC do you use?

 

[Floyd R Turbo]

An additional item, they also carry what they called "Stabilized" MC, they said it is 99% MC, the best I can figure from googling it is this from

http://www.skk-banjaluckapivara.com/invent/agricultural_machine/stabilized_methylene_chloride.html

"A stabilized methylene chloride composition consisting essentially of methylene chloride and stabilizing amounts of mixed amylenes, propylene oxide, butylene oxide and tertiary butylamine."

 

[Acrylics]

Just out of sheer curiosity, what benefit for this ingredient add?

It's similar to methylene chloride, but slower. It allows me to further control the reaction without adding acid. Adding too much acid can make joints look "grainy". I do a lot of joints that will be 40+ lineal feet of 1.5" - need the time to do the joint

Very good to know. I wonder why MC Bond has it then?

idea is that having some in there will help "fill" slight variations. Just doesn't work that way though IME, but all the solvent mfrs use it in their solvents, IPS included. If you check the MSDS pages - you'll see it

Acrylics, what grade of MC do you use?

I don't worry about the grade too much, just the assay. Everything is ACS except MC which is lab grade, but the one I buy assays at 99.9%. Save a few bux that way

James

 

[redneckgearhead]

My work has some large sheets of 3/8 clear "plastic" they are going to trash. I asked and no one seems to know what they are made of....acrylic or polycarbonate or what. Is there any way to tell what it is? Will weld-on "weld" anything besides acrylic?

 

[Floyd R Turbo]

As far as I know, it's really only if they have the paper on them still. There would be print telling what brand and type they are, and you could look that up. Aside from that, I would grab them. I wouldn't make a tank out of it if you didn't know what it was, but you could use it for many other things (practice being #1, if you've never done acrylic work before). Weld-On makes many different products, for many different purposes.

 

[Acrylics]

My work has some large sheets of 3/8 clear "plastic" they are going to trash. I asked and no one seems to know what they are made of....acrylic or polycarbonate or what. Is there any way to tell what it is? Will weld-on "weld" anything besides acrylic?

If it's "crystal" clear it's acrylic - generally. If it's got a slightly grey/blue tint, it generally could be either polycarbonate or PETG. There are quite a few other plastics out there that are "clear" but these would be the most common. Basically, look at the edge of the material - what color is it?

And yes, if it's any of these 3, Weld-on 3 or 4 will work to varying degrees, but I wouldn't use any of them on a tank. Even if it's acrylic, if you don't know what brand - may be good, maybe not. Also a possibility of it being AR coated - would make it impossible to glue without removing the coating.

James