Density of Casting Resin?

[fishordie79]

Hey there TU Folks!

 So my carving has gotten to the point to where I am going to start making masters and doing resin copies. I've got all of the materials I need on the way, other than the resin, and I was wondering......with different varieties of woods you can somewhat judge the amount of weight that the lure will require to sink properly. With resin.....I don't have a clue. How dense/heavy is that stuff? How do you guys typically weight resin casts? Birdshot? Drill and fill? Some other method?

Thanks as usual to all of you! 

[AZ Fisher]

  100% resin sinks like a rock.. I use Smooth-on products and use Micro balloons from Alumilite for buoyancy. Each company has their own name for their filler/micro balloons. You have to experiment to find your own ratio for the sink/float rate you want. You can easily make a resin a bait float, just add enough MB"s.

  The trick to a great swimming bait, is a combo of well placed ballast weights and a Mb ratio that gives you the float/sink rate that you're after. Glides need weight in the bottom, crank downs need more in the nose and a walking topwater will need some towards the tail section somewhere. 

   Some will use birdshot or other types of weights. I don't like birdshot, won't go/stay exactly where I wanted and would wind up resting against the side of the bait and you could see and feel the dimples from the birdshot, then have to do bodywork to cover the blemishes. Search on here for resin/MB ratios, Engineered angler has a vid about it on Youtube, try Makelure vids as well.  If memory serves, for a neutrally buoyant resin bait, you need to replace about 1/3 of the weight of the bait with filler/MB"s,  and don't quote me on that.  I'm sure that someone else here knows for sure, hope this helps...

[TootsMalone]

I personally drill and fill with melted lead. I only have experience with Alumilite White Resin. Use the volume calculators you can find on makelure.com (or alumilite.com, they're both run by alumilite). Once you figure out the volume of your molds you need to convert it to resin. Then i take 9% of the weight of resin needed per mold and add that much of the MB to the mix. You will end up with extra resin the first few times so adjust the mix until you get the least amount of wasted resin and don't forget to redo your MB calculation every time you remove resin. Probably not the "perfect" mix but has been working out well for me so far. 

I think i got the % MB mix calculations from a Engineered Angler video. 

[Vodkaman]

Resins generally have a specific gravity (SG) of 1.2 were fresh water has an SG of 1.0 and so yes, it sinks rapidly.

The more MBs you add the thicker the pour. I managed to get down to an SG 0.64 but I had to inject with an icing syringe.

Most use the pre-mixed resin with MBs, consistent and a lot more convenient.

Dave

[fishordie79]

As usual, you people come through with great advice. @AZ Fisher @TootsMalone @Vodkaman so this is what I gather from your input:

1. Whether pre-mixed in the resin or not, I will need micro balloons. Maybe I will order resins with and without integrated MBs and do some test builds to figure out what works best for me. 

2. Birdshot may require body work after casting. I have seen this in some videos on YT so I'lll try to avoid it if I can. I'm comfortable with the drill and fill with lead method so I may just start with that. 

3. Volume calculators can help determine the resin to MB ratio based on the volume of the mold. I'll keep this in mind should I decide to use straight resin and add my own MBs. 

4. This is gonna require a good amount of trial and error. Of course it is. We punish ourselves through our failures and bask in glorious victory when we finally get it right. I wouldn't have it any other way;) 

Thanks again guys!

[Hillbilly voodoo]

For weighing my resin baits I just use a pure resin layer to weight my lures and pour my resin micro balloon mix on top. The trick to shifting the position of the weight is paying attention to how you position your masters in the mold according to the body shape take into consideration where the pure resin will settle. 
 

for example if you want your bait more weight forward have the nose of your master angled down 

If you are worried about getting it wrong to start make your mold level and prop up one end to adjust the angle when you pour. Take note of the angle that works best and  when you make a new mold adjust the master to that angle 

I don’t use any form of weight in my resin baits. 

[Vodkaman]

Check out my post; Archimedes Dunk Test. this will enable you to measure the density of your test pieces. Of course, you need a gram scale for this.

My gram scale weighs to two decimal places and up to 0.5Kg, but one decimal place will get the job done. 2DP will allow you to measure the MBs accurately by weight.

Keep lots of records for future reference.

Dave

[fishordie79]

@Hillbilly voodoo Great information man! This is an option I will definitely keep open! 

@Vodkaman Thank you for putting together the dunk test! I live in Europe so Metric is all I have available to me;) 

[Vodkaman]

@fishordie79

I have been trying to convert our American friends but they are extremely resistant

Dave

[fishordie79]

@Vodkaman Man I understand. I was born and raised over there but after getting out of the service I stayed here with my wife. Having been around both metric is simply easier and more accurate, as you well know:) 

[Vodkaman]

When I post dimensions or weights, I generally post both, but it doesn't work with density.

Dave

[mark poulson]

8 hours ago, Vodkaman said:

When I post dimensions or weights, I generally post both, but it doesn't work with density.

Dave

Didn't a joint venture Martian probe crash because the calcs. made in the U.S. were in Imperial, while the calcs. made in Europe were in metric?  I'm glad we don't have to worry about that in lure making.  Hahaha

[Vodkaman]

@mark poulson

It has happened a few times. Air Canada flight 143 known as the Gimli Glider, ran out of fuel because calculations were done wrong. These problems will continue until we have unification. USA are dragging their feet with this ancient British system.

Dave

[Hillbilly voodoo]

4 minutes ago, Vodkaman said:

@mark poulson

It has happened a few times. Air Canada flight 143 known as the Gimli Glider, ran out of fuel because calculations were done wrong. These problems will continue until we have unification. USA are dragging their feet with this ancient British system.

Dave

And it makes it difficult for us poor Canadians because we have to learn both systems because our close trade system 

Come on now think of the poor Canadian children who learn metric in school and have to learn imperial on their own time just to function 

If I post any calculations in the future it’s going to be 50/50 metric/imperial just to mess with you guys 

 

[Vodkaman]

23 minutes ago, Hillbilly voodoo said:

Come on now think of the poor Canadian children who learn metric in school and have to learn imperial on their own time just to function 

 

The kids are lucky, their math will improve. I do conversion calcs in my head just for fun. In competitions, the big fish weights are called out in kilograms, I convert to pounds. Multiply by 5, divide by 11

Dave

[Hillbilly voodoo]

6 minutes ago, Vodkaman said:

The kids are lucky, their math will improve. I do conversion calcs in my head just for fun. In competitions, the big fish weights are called out in kilograms, I convert to pounds. Multiply by 5, divide by 11

Dave

I always heard about strange people who do math for fun but thought for sure it was a lie 

 

[Vodkaman]

Read up on Trachtenberg

Dave

Edited December 19, 2019 by Vodkaman

[mark poulson]

Think of our reluctance to convert to metric as our Brexit.