Mold and soft plastics issues

[Saltyboisean]

Hey all! A couple of friends and myself are looking at starting a soft plastics lure company, although mostly just for fun. Neither of them have much experience with lure making, but I’ve been making hard baits for years so naturally it fell on me to come up with the molds, and designs, with insight from them. We decided to start with stick baits, but I’ve ran into a handful of issues that i was wondering if anyone here would be able to help me out with. I’ll try and break down our goal, my process, and issues as well as I can. 
 

The goal: a 2 piece injection mold capable of producing quality soft baits relatively quickly. I’m opposed to using a pre made mold, because I want what we make to be unique, and want to avoid any sort of intellectual property rights issues or anything like that that could come from using someone else’s product for our production. 
 

The process: I started by making a stick bait master out of a wooden dowel rod. Once I had this the way I wanted it, I inset it in modeling clay, added indexing marks, and created a mold box. Next I used Alumilite high strength 2 to create a pour in style mold to create copies of the master. Then I made  another mold box, set in the copies of the master, added a sprew, gates, and indexing marks, and used Vac Master 50 to get the final injection mold. 
 

The issues: the main issue that I’ve run into so far is that the final vac master 50 mold, after removing the masters, is extremely porous and cracked, and almost looks like wet concrete. By no means usable even if just for ourselves. I let each half cure for 6 hours before proceeding, and used mold release each time.
 

I found this out when I went to my buddys house to shoot our first baits. When we found out that the injection mold wouldn’t work, we decided to use the pour in style mold to run some baits to mess around with colors, salt content etc. Go figure this didn’t go according to plan either, our baits came out incredibly soft and stretchy. We were using medium plastisol 212, heated to 325 on a hot plate, stirring consistently, poured into the high strength 2 mold, and let to cool for 15 minutes (until the excess in the beaker cooled and stiffened up). We tried it with salt and without salt and found no major differences. Is this just how plastisol is? Are we’d doing something wrong? In my mind I was aiming more for of a Yamamoto style consistency, but really I wasn’t sure what to expect. 
 

I’m going to get a different mold release for the vac 50, and I even tried brushing the first layer on thinly. Brushing it on helped slightly, but it was still way too porous. As far as the bait plastics, I have no clue. I’m also investing in a 3D printer this week which I’ll use for masters and eventually molds (even though I’d prefer the vac 50 for it’s aluminum content) once I figure out the right filament for molds  

I’m also aware I didn’t leave a whole lot of border space on the 6 bait mold, but I was running out of clay and figured it’d be good enough for a test run  

 

TL;DR

my vacmaster 50 molds are cracked and porous as all get out, and my plastisol even after letting cool for 30 minutes has the consistency of on of those stretchy sticky hands from middle school. 

 

 

Edited May 22, 2022 by Saltyboisean
Cropped out personal info from pictures

[Apdriver]

Welcome to TU, Saltyboi. Custom CNC molds are pretty expensive and that’s really what you need for your own design and enough production to produce baits quickly and in volume. Cavity count is probably the one most important part of production. That costs money. If it was me and I wanted to start a small business in soft plastics, I would settle on a bait (you decided stick bait) and purchase some molds that are already in production. There are some really good ones out there and it’s not like you can reinvent the soft stick bait wheel. That way you can focus on the other stuff that will require a lot of time and effort to develop. Packaging, colors, salt, recipes, clients, production, other equipment needs, etc. No patent infringement using a design from someone that sells the molds. You can’t call it and package it as a Senko. I believe that would be copyright infringement.

[SlowFISH]

I cant speak to the VAC 50 stuff - but using other products like that lead me to believe it wasn't mixed properly and you introduced alot of air when mixing it - which resulted in a all the bubbles/cracks, etc etc  With some of those products you need to follow the instructions diligently (mix volume) and time from mixing to pouring, etc... and even some you'll need to pull vacuum on it to get the air out before pouring it and even after would help.

As for mold design - look at aluminum senko molds - there are alot of issues with your layout as far as spacing, sprue and venting sizes.  Also - with any material besides aluminum - assume you'll want to put a little more space between each bait to aid in cooling.  So your mold either needs to be bigger or you nee to put less cavities in it.

 J.

[jigmeister]

I have made some molds out of platinum cure silicone for full round straight tailed baits with the masters oriented vertically in a row suspended off the bottom with fine gauge wire . You can put a big sprue at the top of the mold for ease in hand pouring and removing the bait . after cooling the baits pull straight out due to the give of the mold and bait and no flashing to contend with . The cured Platinum cure silicone is transparent so you can see the plastic when pouring in too. 

The Platinum cure silicone is expensive but so are machined aluminum molds 

[BTL]

I wanted to do the same thing. Didn't want to have something custom machined, so I tried to make my own mold out of Vac Master 50. Went over the instructions and watched the videos over and over, but it just did not work for me at all. I used an absurd amount of mold release too. Tried making two different molds and both were a disaster. I will never bother with it again.

 

I don't know what kind of plastic you're using, but the medium plastisol I got from Alumilite was the same way. It could just be that you're not stirring it enough though.

 

If you want to be original and also produce real quantity, it's probably just best to bite the bullet and get a custom mold. Or better yet, just do what Apdriver said. 

[Shepherd]

CNC molds is what you want. It's often a common first timers misconception that they need more cavities. When the reality fewer cavity shoot better. Then comes your packaging. I found that clear bags made in the USA is a place to get your packaging when you decide what type and the size dimension packaging you want you want clear bags to send a stencil to your graphic designer in which you have designed what you want your bag to look like and they can put it on your bag. Then you want to find a good plastisol provider I will suggest MF or lurer craft. You can also get your coloring and your glitter from those providers as well. If you look at the top of the soft plastic form there will be a soft plastic code recipe book you can download in which there are some beautiful colors and shelf colors that zoom, Berkeley, and other popular name brands use. It also includes some of TU members own personal recipes you'll be good to go after that

[Senkosam]

Plaster of Paris has done well for me.

[DaveMc1]

On 6/8/2022 at 4:04 AM, Shepherd said:

Then comes your packaging. I found that clear bags made in the USA is a place to get your packaging when you decide what type and the size dimension packaging you want you want clear bags to send a stencil to your graphic designer in which you have designed what you want your bag to look like and they can put it on your bag. 

Just a clarification, Clear Bags is a USA based company but all of their bags are manufactured in China. 

[canuck 2]

All the plastisol products that I have read about and have used require at least one heating to 350*f for virgin pure plastic to get the chemical reaction and consistency. And that needs to be an accurate temperature measure while stirring. Are you sure your 325*f heating is not causing a lot of your issues? Plastics wise . I would try pouring again in a  proven mold with hotter plastic and add some stabilizer to see if things improve for you.