A better way to mix epoxy... maybe

[pd711]

I came up with this in an effort to mix epoxy with the least amount of air bubbles:

Anyone who worked with Corian 20+ years ago will remember that you used to to squeeze a tube of part A into a larger tube that contained part B and then you clamped the tube into the end of your random orbital sander and let the action of the sander mix the two parts. It worked great.

So I took this idea and made an epoxy mixer out of an old ROS I don't use any more.

I built a box to hold the ROS upside down and clamped to the table. Then made a platform to hold a Dixie cup with the epoxy in it.

The last two pics are of epoxy poured right from the cup. No bubbles.

[wtnhighlander]

Neat trick, thanks!

[Coop]

Cool idea. So the vibration alone mixes it? 

[ChrisG-Canada]

Did the epoxy cure properly?  That’s the ‘proof’ everything was mixed properly.

[Isaac]

Reminiscent of how concrete is mixed/consolidated using a vibrator.

[pd711]

17 hours ago, K Cooper said:

Cool idea. So the vibration alone mixes it? 

the orbital action of the sander pad mixes it.

1 hour ago, ChrisG-Canada said:

Did the epoxy cure properly?  That’s the ‘proof’ everything was mixed properly.

Yes. I mixed hundreds of Corian epoxy kits using a ROS 20-25 years ago.

 

[Jean [Fr]]

I've been a huge user of epoxy for 30 years. I've done maybe all you can do with epoxy, from simple gluing to hi-end composites.
I've got all you can dream of to work with resin, from vacuum chamber to pressure mixing gun.
Please don't get me wrong, I'm not the kind of guy who will spend extra time or effort if there's a safe way do save on those.
But I won't trust this method because it can't produce a consistent mix, even with a very fluid epoxy.

In the best scenario, vibrations will produce a vortex inside the cup, but this is not guarantee, especially with thick epoxies or during cold days.
The vortex will just mix the epoxy in a cone shape in the middle-top area of the cup.
Sides will not be mixed the same way. Probably you get unmixed epoxy on the bottom corners of the cup.

I won't risk a bad bond with sorcerer's apprentice tricks anyways.
Corian is acrylic resin with mineral charges, this is different from epoxy or polyester.
You want to feel the mix and the way the resin reacts that particular day, because each day is particular with epoxy.
Bubbles are a factor only in vacuum stratification because it will expend (a lot!).
For a glass finish top you get rid of bubbles in seconds with a gas torch.
There's three important points with epoxy : proportions, mix and climate (temperature/moisture).
You're right on this or you fail. Simple as that.
Mixing epoxy by hand is not difficult or time consuming, why would I save on one of the most important factor ?
Resin can be tricky sometimes, I don't want to introduce another hazardous parameter in the recipe.

Nowadays, there's not much to invent or to learn about stuff.
If you can't find the method in industrial applications, there are reasons why.
 

[Tpt life]

This is in response to the negative post above. The concept is simple to verify. Start with water and dye in a clear cup. Move to something thicker like vegetable oil. You could even drip a drop of transtint in some epoxy in a clear cup and watch it to verify. To avoid it because it is not already done is poor logic when verification is simple to achieve. That said, raising that concern is valid. 

[pd711]

1 hour ago, Jean [Fr] said:

I won't risk a bad bond with sorcerer's apprentice tricks anyways.
 

I've been called worse. A sorcerer's apprentice would make me kinda like Harry Potter

 

Will it work for all epoxies? I have no clue and  I wouldn't even begin to think it would. But in my little 20 x 15 basement shop world with the one epoxy I use I can say it works. For me.

[wdwerker]

I think I would give each batch a quick swirl with a stick before vibrating it.  We swiped our fingers up and down the Corian glue pouch just to give it a preliminary mix. 

[Tom King]

I don't know if it matters with epoxy, but from working on boats with polyester resin, followed by gel coat, it was wise to use wax-free mixing cups, or some wax could float to the top of the lamination, and prevent the gelcoat from getting a good bond.  From the habit of doing that, I always keep some sleeves of different sizes of wax free cups, and that's what I use for large mixes of epoxy.

I kind of remember the vibratory trick for mixing Solid Surface glue, but that was in the early 1980's for me when I had switched from Formica for countertops, before Granite took over in the early '90's, and I know I didn't own a Random Orbit sander in the early '80's, even if they were available.  I was thinking it used the 1/4 sheet vibratory sander.

The first glue mixer setup I remember had a one shot tube that mixed by pushing it out with a caulking gun, but you had to change the pushing disk in the caulking gun to a special one that came with each combo tube of adhesive.  I remember that working really nicely, but they went to something cheaper after that.

[Jean [Fr]]

3 hours ago, C Shaffer said:

This is in response to the negative post above.

Well, I'm sorry you consider my two cents as negative. Maybe I sound too strong as usual. I apologize for my bad english.
 

3 hours ago, C Shaffer said:

 To avoid it because it is not already done is poor logic when verification is simple to achieve.

If you know a minimum about resins, you will agree how important a good mix is.
There's methods to try to avoid issues (multiple long pours, double cup mix...) because proper resin mixing can be tricky.
I usually die the hardener prior to mix. This is not risk free, but it gives a valuable indication of the achievement of a good mix.
Sometimes you're not focused enough while mixing (especially on long days of epoxy stuff by numbers) and even if the colour looks even,
the mix can be not stirred enough, and the punishment comes quickly : weak bond and/or never cure areas.
So, I would not be confident about the "simple verification" process.

About the "is not already done" thing, we should stop just a minute and use common sense.
Resins and polymers is an important, profitable and innovative industry for several decades.
Since the 50s, every day, thousands of qualified R&D engineers all over the world works on polymer resins.
There's a variety of possible mixing solutions, including vibratory slab, which is definitely not a recent technology...
Would you believe that nobody tried except a man in his garage who lost the recipe during 20 years ?
Let's agree any possible mixing methods has been obviously tested several times during the passed 60 years...
If the vibratory mixing of resins were at least workable, this is so simple that you could find several in any shop,
instead of expensive or slow mixing systems available today.
We're mostly in the copy era, sometimes we can improve existing concepts, but we don't have much to invent.
Only hi end technology invents nowadays.

All the contemporary resin mixing machines have a slow motion mechanical stirrer (except pressure guns).
Note in the concrete industry vibratory technology is used to remove bubbles and compact the mix,
with long vibratory rods deep inside or this does not work, but this is to stabilize the concrete, not for mixing.

Actually, the single vibratory mixing system I know is for paint mixing when you ask for a custom colour at your local DIY store.
That industrial machine works obviously much harder than an orbital sander.
Even if paint is more fluid than epoxy and paint dies are even more fluid, The mix is not complete at all after this 5mn process.
Back home, you have to stir your paint for a long time for a proper mix.
The bottom and sides area did not even get the dies. That's no surprise to me.
IMHO, the single benefit of this system is to have no stirring tool to clean between uses.

 

[Tpt life]

24 minutes ago, Jean [Fr] said:

Well, I'm sorry you consider my two cents as negative. Maybe I sound too strong as usual. I apologize for my bad english.
 

If you know a minimum about resins, you will agree how important a good mix is.
There's methods to try to avoid issues (multiple long pours, double cup mix...) because proper resin mixing can be tricky.
I usually die the hardener prior to mix. This is not risk free, but it gives a valuable indication of the achievement of a good mix.
Sometimes you're not focused enough while mixing (especially on long days of epoxy stuff by numbers) and even if the colour looks even,
the mix can be not stirred enough, and the punishment comes quickly : weak bond and/or never cure areas.
So, I would not be confident about the "simple verification" process.

About the "is not already done" thing, we should stop just a minute and use common sense.
Resins and polymers is an important, profitable and innovative industry for several decades.
Since the 50s, every day, thousands of qualified R&D engineers all over the world works on polymer resins.
There's a variety of possible mixing solutions, including vibratory slab, which is definitely not a recent technology...
Would you believe that nobody tried except a man in his garage who lost the recipe during 20 years ?
Let's agree any possible mixing methods had been obviously tested several times during the passed 60 years...
If the vibratory mixing of resins were at least workable, this is so simple that you could find several in any shop,
instead of expensive or slow mixing systems available today.

All the contemporary resin mixing machines have a slow motion mechanical stirrer (except pressure guns).
Note in the concrete industry vibratory technology is used to remove bubbles and compact the mix,
with long vibratory rods deep inside or this does not work, but this is to stabilize the concrete, not for mixing.

Actually, the single vibratory mixing system I know is for paint mixing when you ask for a custom colour at your local DIY store.
That industrial machine works obviously much harder than an orbital sander.
Even if paint is more fluid than epoxy and paint dies are even more fluid, The mix is not complete at all after this 5mn process.
Back to home, you have to stir your paint for a long time for a proper mix.
 

Lots of words for what is easy to verify was my only point. I did not want it to seem more than that. I painted commercially and cannot stand by what you said of paint mixers. Pouring many thousands of gallons through a screen did all the extra mixing needed. Perhaps store mixers differ? 

The epoxy I use has a definite yellow tint to the hardener until it is solution. Again, you would get a pretty good feel from two minutes of this process to know if another five or ten is effective. I just don’t like the logic since I have seen such “stupid simple” solutions to long standing problems as they say. 

With respect, you only said you would not trust it without verification. I truly only wanted to suggest a simple way to see if any likelihood exists. Carry on. I have enjoyed the challenge and discussion. 

EDIT: The OP has his own verification with Corian bonding. Check his second comment. 

[Tpt life]

BTW, I don’t own a 1/4 sheet sander or I’d start verification myself. What is the stroke measure of the sander in the OP? 3mm?

[Jean [Fr]]

2 minutes ago, C Shaffer said:

With respect, you only said you would not trust it without verification.

Well, you're right. I will not give it a try, because I do not have much time for experiments and I have proper mixing devices.
In a way, I'm an old resin user (boatworks, like @Tom King) and experience brings some reflexes.
Just like a too small tenon, or a weak joint, you get it at first sight. I understand it can be considered as subjective or presumptuous.

If you give it a try, do it with a reasonable batch, at least 10oz. IMHO small batches should not show that much.
Hardener first, resin on top (the opposite should be less efficient), and let's see how good the mix will be.
Then you should find a way to get resin from the lower corners only (maybe from a hole in the bottom of the cup).
You will probably note than the gel and/or curing time is different with resin from the top and from the bottom.
That will demonstrate the mix is not even. And the problem should be increased with Polyester resin, and less present with 1:1 ratio resins.

Good luck

 

[BillyJack]

We just pour and torch. Simple...

[Chet]

58 minutes ago, BillyJack said:

We just pour and torch. Simple...

The first and third picture looks like engineered lumber, is that what it is?  What are the for?

[BillyJack]

BurgerFi.............Parallam

[BillyJack]

[pd711]

3 hours ago, C Shaffer said:

BTW, I don’t own a 1/4 sheet sander or I’d start verification myself. What is the stroke measure of the sander in the OP? 3mm?

I have no idea. It's an old cheap B&D sander that's loud. Very loud.

[wdwerker]

Usually with old and cheap tools loud is a foregone conclusion !

[Pondhockey]

I absolutely appreciated the OP and the following discussion!  Thanks to all.

[Pondhockey]

OK, so more piggy backing:

I'm filling voids in a slab with (tinted) epoxy.  The voids are somewhat like a Southeastern limestone cave - they wander and branch and come out in unexpected places.

I'm doing this in a North country garage that is usually kept at about 52F.  The spec's on the System Three resin and (#1, fast) hardener claim a 15 minute gel time, and 2 hour "tack free" time at 77F.  Figuring that every 10C (18F) drop in temperature doubles the times of the associated chemical reactions, I expect about a 40 minute gel time and maybe a 5 hour tack free time in my garage/shop.  While I care about both times, my initial concern is about the gel time, when the epoxy stops running.

My initial approach was to heat the garage during the curing process (it's a 1700 sq foot garage/shop.)  Then I thought better of it and started looking for a space heater and planning to build a tent.  Then (duh - I'm not the brightest light in this house) I wondered about bringing the epoxy components inside the utility room (or the mechanical room, which stays even warmer.)  I would mix them at the higher temperature, perhaps let them sit for "a while", and then apply them and let them cure in the colder shop.

And finally I thought of you guys.  So I'll ask this in a open way:  do any of you have any relevant thoughts or advice or (even better, experience?)

[BillyJack]

Your better to get the slab to the correct temperature and not just the room..