Bubbles

[DoubleT]

I have a question for the folks making baits out of resin. I am using the Alumilite amazing white and micro balloons with a two piece silicone mold. The problem I am having is that I am getting bubbles formed along the back of my lure. I have done some research and see where a pressure chamber will eliminate the bubbles. I also read that it doesn't necessarily remove them, it basically crushes them to microscopic size. So, here is the question. I am having problems with consistent sink rates due to the bubbles that are formed in the back of the lure. If I cast them under pressure will I still have the inconsistencies due to the bubbles not actually being removed but just crushed to microscopic size? Maybe I'm overthinking it but it just seems to me that I will just be taking large bubbles and making lots of smaller ones. Technically no change. Thanks for any info that you can offer.  

[mark poulson]

I don't cast baits, but it seems to me, if casting under pressure produces micro bubbles, that would be a good thing.

First, there won't be any large bubble voids at or near the surface of the bait, which could cause cosmetic problems or weak spots.

Second, if the micro bubbles still rise in the material before it sets, and you pour with the belly down/back up, the bubbles will be higher in the bait, and that will make them more stable, because the back will be more buoyant.

But that's just looking at it from an outsider's perspective.  

People who actually pour resin baits will know a heck of a lot more than I.

[SW Lures]

This is interesting question, In the field that I'm in. Bubbles/porosity (gas pockets) make objects weaker. However in baits you need them in resins, wood, plastic cavity blanks, soft plastics and pvc to have buoyancy. The more in the back the bait should keep the bait upright. You could and should if needed to put ballast in the belly to keep the plug upright and swimming true. Like Mark, I'm a person looking in.....well somewhat.

[Musky Glenn]

I would probably treat them like moving parts in a car engine and balance them to a set standard that works for you. Then they would all be the same. Good luck.

[woodieb8]

its very doubtfull the bubbles created the buoyancy issue,unless all the mixed micro-spheres migrate when pouring. if that's true you will have a density strength issue to follow. as finishing you can use any paintable filler for the tiny voids.. we use urethane foams in our molds here on some bait lines we manufacture.

[Anglinarcher]

On ‎6‎/‎30‎/‎2017 at 5:04 PM, DoubleT said:

I have a question for the folks making baits out of resin. I am using the Alumilite amazing white and micro balloons with a two piece silicone mold. The problem I am having is that I am getting bubbles formed along the back of my lure. I have done some research and see where a pressure chamber will eliminate the bubbles. I also read that it doesn't necessarily remove them, it basically crushes them to microscopic size. So, here is the question. I am having problems with consistent sink rates due to the bubbles that are formed in the back of the lure. If I cast them under pressure will I still have the inconsistencies due to the bubbles not actually being removed but just crushed to microscopic size? Maybe I'm overthinking it but it just seems to me that I will just be taking large bubbles and making lots of smaller ones. Technically no change. Thanks for any info that you can offer.  

 

OK, you have had good answers so far, but I am going a little off the reservation on my answer.

I use Alumilite White and microballons extensively and have NEVER had bubbles like you seem to be talking about, unless I created them.  It would help to see a picture of it so I can help you out.

There is a lot of answers on this site that suggest that the microballons will migrate to the top once poured, but this, in my experience, is just silly.  Alumilite White is pretty thick and cures in about 3 minutes.  You have to mix the stuff up and get it poured pretty fast.  Further, the microballons are so small they will not show up as bubbles no matter what.  Assuming you mix it for about a minute, that means you have 1 to 2 minutes to pour.  10 to 15 minutes total you can demold it.  Simply stated, the microballons cannot migrate in the thick liquid in that time.

Still, if you have bubbles, then you have bubbles and we need to get to the bottom of it.  The only time I have had anything like it was when I tried to drop a couple of drops of water into the mix to see if I could get it to foam a little and lighten up more.  It worked, but was extremely unpredictable.  Is there a chance that your product has been contaminated?

Well, too many questions to ask.  Post a picture, close up, and I can do a better job of trying to help you.

As for casting under pressure, yes, it will make your product very consistent and will, for all practical purposes, eliminate the bubbles.

PS, this same information applies to Smooth-On as well.

[DoubleT]

This bait was cast using alumilite regular tan which has a around a minute shorter pot life than amazing white. You can see the bubbles along the back. I feel sure they are throughout the bait but mostly closer to the back due to the pour hole on the mold is in the center of the back. Not all of them are this bad but all of them have at least some small ones. This is the reason I feel I am getting some inconsistencies in sink rate. The baits are made with the same amount of resin, micro balloons and weighted exactly the same.

Im pretty sure the bubbles are created during the mixing and pouring. Its tough not to get bubbles when mixing the micro balloons into the resin and also pouring into the mold while racing the clock.  I mix equal amounts of micro balloons into part A and B. After doing that bubbles will form on the surface in each container. Not sure how to eliminate that. 

I got my pressure pot and was able to do some testing yesterday. Needless to say It sent me right back to the drawing board. This was my first attempt at casting under pressure. 

 I used the same amount of material and when cast under 40 psi this is what I ended up with. With all of the bubbles collapsed/compressed it emptied the pour hole in the mold and left a void in the back of the bait. So, I guess now its time to to make some changes to the mold. Looks like I will need to increase the size of the pour hole in order for it to hold enough extra resin to fill the mold once under pressure. I can say this though. There weren't any visible bubbles which I was happy with. 

Any thoughts? If I'm missing something please let me know. Thanks

Edited July 2, 2017 by DoubleT

[woodieb8]

whats shown will not change. its an inherent issue with urethane foams.. the only issue of sink rate would be densitys involving expansion. that can be caused by temperature when pouring . under 72 degrees expansion would be less..as I stated before the small pitting can be filled with lepages wood filler and sanded.. if anyone solves this issue feel free to share. we pour dozens of gallons yearly and have become accustomed to this.

[ravenlures]

I just wonder if you are using too much micro balloons it seem 33% is a little bit to me, I would believe that it would be to thick and movement around a wire makes worse.  One thing you could try is mix resin in with the foam.  for that you will have to come up with a new formula. Also try a vibrator plate when you are  pouring.

Wayne

[SW Lures]

Woodie, I'm learning from this as you and I have communicated about in the past. The smaller voids I understand and repair is just something we do, but the large opening in the last picture seems to be a venting issue. Maybe even more of a set up problem before a full filling of the cavity.  Why did that happen?

Dale

[mark poulson]

1 hour ago, DaleSW said:

Woodie, I'm learning from this as you and I have communicated about in the past. The smaller voids I understand and repair is just something we do, but the large opening in the last picture seems to be a venting issue. Maybe even more of a set up problem before a full filling of the cavity.  Why did that happen?

Dale

DoubleT said, "Looks like I will need to increase the size of the pour hole in order for it to hold enough extra resin to fill the mold once under pressure."  He's on the right track.  Under pressure, as the air is pulled out of the resin it shrinks, so, just like with a bigger sprue in hot plastics, he needs a reservoir of resin that can be pulled down into the mold as the air is pulled out.

Edited July 2, 2017 by mark poulson

[woodieb8]

our pour hole is at the highest point,vent hole in rear top of our molds. when expansion happens we block the pour/sprue hole. back pressure forces foam micro bubbles to collsape creating a harder denser body.. we wash bodies in hot dawn soapwater to remove any release wax. then sanding. . wish I knew how to downsize pics. I'm one of the old guys building baits ,... I hope this helps someone out.

[Anglinarcher]

Double T, call Alumilite and talk to Mike Faupel, but I am positive that you are incorporating contamination into the system when you are pouring, moisture or air, or both.  Because I cannot stand there and watch you, I can only guess at what is causing it, but it looks like moisture contamination.  It could be water in the Microballons, which can absorb moisture if the cover is left off in high humidity areas.  It could be water in the Part A and/or Part B, which again can absorb moisture the same way.

If you are pouring a lot of it and use the resin and microballons up quickly, then you may not need to close the containers.  I close every time I am done and have no issues.  If you really need it, you can get Bloxygen to prevent moisture contamination in the resins but I have never needed it.  https://www.alumilite.com/store/p/962-Bloxygen-Moisture-Barrier-41oz.aspx

Finally, I know that the stuff must be mixed fast, but I take a minute and that does not require me to mix so fast that I incorporate large air bubbles.  Consider some slower mixing and see if that is the problem.  I hang my hat on the above explanation, but it is inexpensive to at least try a batch with slower mixing.

Now, for some stuff that will probably get me in hot water.  I call Blarney on some of the comments made in response.

1) "whats shown will not change. its an inherent issue with urethane foams".  First, Alumilite white, tan, etc., are resins, NOT foams.  This is not inherent or even common to Alumilite Resins.  Foam was not even mentioned until I revealed that I had tried to get it to foam.....that was MY MISTAKE.  Too much information can be a problem, and I apologize for that.  Alumilite does have Foams, and I use the 320 and Alumifoam quite a bit, and while they self skin well, once in a while I do need to repair due to bubbles.  They are not weakened by the bubbles. 

2) "using too much micro balloons it seem 33% is a little bit to me"?  The max amount of microballons is an equal volume of microballons combined with the weight of Part A + Part B.  I have included a chart that relates the microballons to Resin, and other densities of Alumilite products.  Actually, 33% by volume is nothing. 

3) "One thing you could try is mix resin in with the foam."  Again, he is NOT USING a foam, he is using a resin.  I strongly do not suggest mixing a resin with a foam.  I see only issues relating to it.  Still, at least call Alumilite first.

4) "large opening in the last picture seems to be a venting issue. Maybe even more of a set up problem before a full filling of the cavity".  That was the result of putting the casting material under pressure.  This is a lot more then I have seen when I did it, indicating to me that the bubbles are throughout the pour.  You already know my opinions on that.

5) Mark, you are dead on.  Fix the problem and this won't be necessary, but your suggestion will work well, except that the material will be more dense, heavier, then he originally experienced.

6) "when expansion happens we block the pour/sprue hole. back pressure forces foam micro bubbles to collsape creating a harder denser body.. "  OK, this tells me tons. 

On ‎6‎/‎30‎/‎2017 at 5:04 PM, DoubleT said:

I am using the Alumilite amazing white and micro balloons with a two piece silicone mold.

 

14 hours ago, DoubleT said:

This bait was cast using alumilite regular tan

Alumilite White or Alumilite Tan do not expand, with or without microballons.  If it is, then you have contaminated the materials.  Microballons are tiny hollow glass spheres; they do not collapse. 

OK, by now I am sure the I have offended almost everyone, but the record has to be made straight.  I have tested this stuff over and over.  I am the one that made the chart for Alumilite.  If you are getting expansion, more than perhaps a 2% expansion with the resins, then you have either product contamination or a bad mixing procedure.

Now I will set back and take the rebuke I am sure I will get, justified or not.

Edited July 3, 2017 by Anglinarcher

[DoubleT]

5 hours ago, woodieb8 said:

whats shown will not change. its an inherent issue with urethane foams.. the only issue of sink rate would be densitys involving expansion. that can be caused by temperature when pouring . under 72 degrees expansion would be less..as I stated before the small pitting can be filled with lepages wood filler and sanded.. if anyone solves this issue feel free to share. we pour dozens of gallons yearly and have become accustomed to this.

 

Unless I am confused, I'm under the impression that urethane casting resin actually shrinks (in the thousandths) while curing. Urethane foams on the other hand are a totally different story. They can expand up to many times their size. As far as casting under pressure vs. not, when I cast the lure under pressure there were no visible bubbles. Absolutely Zero. 

I made about a half dozen lures prior to getting the pressure chamber. I was filling the visible holes with bondo and was pleased with the results. Although the lures were made exactly the same and had exactly the same amount of weight in the belly the sink rate was very inconsistent. One actually floated. I didn't find this out until I had airbrushed them and applied the topcoat. Oh well, I needed practice in that aspect as well. 

Thanks for all of the help and I will keep you guys posted on the progress as I move forward to modifying my mold. 

Thanks

 

[DoubleT]

Anglinarcher. Thanks for the info. Your post popped up seconds before I posted mine.

 

[Anglinarcher]

2 minutes ago, DoubleT said:

 

Unless I am confused, I'm under the impression that urethane casting resin actually shrinks (in the thousandths) while curing. Urethane foams on the other hand are a totally different story. They can expand up to many times their size. As far as casting under pressure vs. not, when I cast the lure under pressure there were no visible bubbles. Absolutely Zero. 

 

Take time to read my last post that was a little before yours.  It will save you a lot of time, and money.

[DoubleT]

Anglinarcher that is some very valuable info an I have stared at your chart in the past while scribbling on a piece of paper till my eyes were crossed. I actually printed it out a while back to use for reference.  I will definitely be more mindful while mixing the balloons to the resin and also while mixing the two parts together. Have you ever used more than 100% micro balloons? The bait that I am working on is a rather large musky glide bait. Once cast under pressure with 100% micro balloons the bait still didn't have the buoyancy that I was hoping for. It floated but I didn't have to add much weight in the belly to get it to sink. Thanks for the help.

Edited July 3, 2017 by DoubleT

[mark poulson]

3 hours ago, Anglinarcher said:

Take time to read my last post that was a little before yours.  It will save you a lot of time, and money.

"Now I will set back and take the rebuke I am sure I will get, justified or not."

50 lashes with a wet noodle!

[Anglinarcher]

Yes, I have and do use over 100% microballons, but not for production baits.  Over 100% is terrible to pour, inconsistent filling in the mold, and it starts to get pretty soft.....but, it has a purpose for me.  I often start out with a rough shape I want to work with, then I make a master mold out of that rough shape and then pour some resin with over 100% microballons.  It has no grain and is softer then cedar and most woods at that point, so It is easy to shape with a sander, a rasp, a file, etc.  But, it would take far too many microballons to ever get it to float high enough for your proposes.  Still, Mike of Alumilite did do this and if the shape is simple enough, it will work.  The following will give you and idea of how he did his Muskie Glide Bait.

http://www.makelure.com/store/pg/54-How-To-Videos.aspx#prettyPhoto/7/

When Alumilite came out with Alumifoam they sent me a sample to test and work with.  I discovered it had the density of cedar, was much more consistent, self skinned (but does sometimes have  cosmetic bubbles to fill), and was almost impossible to break.  I had a video on YouTube but the email account I had attached to it was compromised and when I closed it down I lost my YouTube channel, and I had failed to keep a copy.  I molded up a sample lure and used a rod and line to slam it into concrete, hammered it with a hammer, and the stuff just totally resisted damage. 

Larry Dahlberg of "Hunt for Big Fish" was also testing it and he made lures for South American Wolf Fish which destroy commercial lures; it held up extremely well.   I believe he used it for many species of big toothed critters that otherwise sank lures.  Several of his shows showed it at that time, and fish that would punch holes in commercial lures and sink them just scratched the surface.

If you use Alumifoam, you should use a stiffer silicone mold, at least you need to clamp your mold and allow sufficient openings for the foam to expand so the shape stays the same and does not deform due to the pressure of the expanding foam.  But, the results are a lure that no Muskie, no Tiger Fish, no Golden Dorado, will ever destroy.  The down side is that you won't ever have to replace lures due to damage, you can drive a truck over them, replace bent hardware, and keep fishing.  LOL

So, Alumifoam is more difficult to learn, but it will do exactly what you want.  They don't have a video up showing this, so I will try to get one up in a month or two (down with health issues myself right now) in case they cannot get one loaded.

The other option is to pour a standard resin shell, then fill the empty shell with a 310 or 620 foam.  This is a two step method and is harder to get right, so I don't suggest it if you can use Alumifoam or the Resins.

I hope this helps, let me know if I have missed anything.

 

[Anglinarcher]

34 minutes ago, mark poulson said:

"Now I will set back and take the rebuke I am sure I will get, justified or not."

50 lashes with a wet noodle!

I probably deserve worse then that Mark.  LOL

Edited July 3, 2017 by Anglinarcher

[woodieb8]

were all learning every day. .we have become mad scientist.

[SW Lures]

Thanks everyone, that is what I was thinking  but was not sure if I was right or not. Well somewhat right.  I have been pondering starting pouring plugs.

AA (Anglinarcher), I smiled when I read that you use rasp and files, I thought I was one of a very few that does that.

Nah Mark, in the long run the answer was totally explained. That is the most important thing for Double T.

Thanks,

Dale

[DoubleT]

Thanks for input guys. All of the information was extremely helpful. Now I am rethinking the way to go about building my bait. Looks like rigid foam may be the route I need to take. I'm sure there will be bumps in that road as well. 

[mark poulson]

9 hours ago, Anglinarcher said:

I probably deserve worse then that Mark.  LOL

Okay, make it 60!

 

Getting back to the OP's problem, sounds like that Alumifoam is a great product.  Can it be machined like wood, so ballast and hardware locations can be changed, without ruining the bait?

[DoubleT]

35 minutes ago, mark poulson said:

Getting back to the OP's problem, sounds like that Alumifoam is a great product.  Can it be machined like wood, so ballast and hardware locations can be changed, without ruining the bait?

 

I'm interested in how consistent it will be from lure to lure.  If two lures are constructed in the same manner will they act the same? It is apparently some super tough material once fully cured.