Beginner from Oz - mould HELP (rtv, resin/bondo - qu re: materials and tech)

[slipperybits]

The DIY SP scene in Australia seems to be in its infancy. In fact, in fishing and tackle forums I haven’t encountered a single thread on the subject. Similarly, the products and accessories are unheard of over here.

I am however determined to start making my own SP lures. Mainly swim and jerk baits in the 3-5” category for estuary and salt water use.

Anyhoo, at considerable expense I have had shipped from the U.S. a gallon of M-F Supersoft, along with colors and glitter etc. What I really need is some guidance with the mould making process.

My intention is to use existing SP’s as masters to create a 2-piece mould. I have read as many threads, videos and tutorials on the subject as I can find, however there are gaps in my understanding that I am hoping some more experienced builders can fill.

Mould Material

Originally I purchased some water putty for the job. However, after further reading I returned this and began to consider polyester resin, Bondo and RTV silicone.

Resin/Bondo

First of all, I had great difficulty finding anyone in my local hardware who knew what Bondo was. Eventually one helpful store hand described it as the same as polyester resin, but a thicker consistency, though they didn’t carry any. Is Bondo a generic name? What other names might people call this product in Aus and where might I source some?

As for the resin/bondo mix; what kind of consistency would I be looking for? What would be a general guideline for resin/bondo ratio? Would I be able to sink the soft SP in the mix easily, and would it release the lure easily after curing? Would the second half of the mould release easily from the first? How long would I let it set before attempting to sink the SP bait halfway in the mould?

RTV

It seems that the price of bondo and resin would not be much more economical than using RTV (though there appears to be many different types of RTV available). Really I am looking for the most durable, user friendly and accurate medium to make my mould. What would be the relative advantages / disadvantages of RTV over resin/bondo?

Pour Hole

Carving a pour hole out with a steak knife sounds a little crude to me. I considered using a tapered piece of wooden dowel and placing the tapered end at the head of the bait and the other end at the edge of the mould; sinking it halfway with the bait then pouring over it with the second half of the mould. What would be a general guideline for the diameter of the pour hole for 3-5” baits; tapered and open ends?

What are people’s thoughts on the dowel idea? Any better/easier solutions?

What is the ideal position for the pour hole; head, top? I guess the top placement allows the pouring of laminated baits (laminated means more than one color right?)

Air Hole

Is it necessary to incorporate an air hole in my mould, to allow air to escape when pouring? At the moment I am considering a section of nail sunk near the pour hole to create the air hole. Peoples thoughts and suggestions?

Apologies for the barrage of questions, but because I live in a remote part of Aus and am currently in the city on holidays I want to try and buy everything i need before i have to return home. As I said I have taken time to read the tutorials and relevant threads but still have lots of questions.

Any constructive advice would be GREATLY appreciated. Thanks and kind regards

Jim.

Edited July 8, 2009 by slipperybits

[gone2long]

O.K. here's one man answer:

Bondo is a trade name for fiberglass resin it is used in the automotive industry as well as the boating industry it is the goto material when I make 2 piece molds as it turns rock hard when cured but can be machined easily. De-molding is also easy provided you are using a plastic wormbait as your positive. Don't forget you will need registration pins on a 2 piece mold.

RTV is nice to work with but I only use it for 1 sided baits i.e. chunks, craws it releases well and is flexible but is pricey.

As to a pour hole if you look at a real aluminum 2 piece mold it is approx 1/2 " in diameter and around as deep, again be careful what you use if using resin or it will never de-mold (Use release agent)

As to a vent what I do is straiten out a paper clip (larger type) and use it as a skewer to put the bait together, if you leave it protrude from the bottom of the bait it will act as your vent, it also works well when using different parts of baits to make a new creation.

Also consisder POP (plaster of paris) this is a very cheap but yet productive way to make 1 & 2 piece molds you can find more on that if you search POP.

Just a suggestion being your costs are high, only mix batches of 4 oz at a time when first learning as you will foul up now and again, most of the guys here use 4 ozs as a base for their color recipes which again you will find on the forum.

Good luck!

Chris

[Husky]

Hey Jim,

If you're making "Half Round" baits, Ones that are cast in 1 piece molds, I have put up a thread on how to make that type of mold, quickly and inexpensively. Click here.

If you're pouring silicone, Plaster or Durhams Putty, Affix your model to a flat, smooth, non porous, clean disposable, surface with Crazy Glue or dual sided tape. Enclose it in a box which will allow you to encapsulate the model. You do not need to have much clearance on the sides or over rhe model. 1/4" is sufficient. With Plaster and Durhams, you must be sure there are no undercuts or the model can get trapped if it is made from wood or an other rigid material.

For more complex procedures, I recommend you go to Freemans site and click on their Video Library.

All your answers will be addressed there.

Mike P

[slipperybits]

Hmmm... Thanks for the replies.

Mr Bilky, you say that Bondo is a trade name for fibreglass resin - but this has confused me.

Numerous techs on this and other sites call for a mixture of bondo AND fibreglass resin - the bondo serves to thin thicken the resin to a workable viscosity.

Here is an example of moulds made by Artifical All The Way using a combination of resin and bondo

http://www.tackleunderground.com/forum/soft-plastics/13670-my-new-sluggo-mold.html

I know Bondo make a lot of different products, i.e. resins and automotive and marine fillers. Could the Bondo refered to in techs be a polyester based filler type material?

The bondo used in the molds that i have seen has had a pinky/putty colour. Whereas the fg resin is generally clear.

If they are one and the same thing - it dosn't make sense.

Quote from 96dak

"Resin and "Bondo" are both polyester based products, and use the same catalyst (MEKP), you mix the 2 together before adding the hardener, it will thicken up the resin and actually prevent a lot of the shrinkage inherent in resin (which will shrink 7 - 10% while curing)"

Do you use the clear, highly viscous - fg resin on its own to make the 2-part moulds?

The paperclip idea for an air vent is cool - where exactly does it protrude from - does it actually come right through the mould?

As for a pour hole - what would be a good way to create the correct shape for pouring?

Thanks again

Jim

Edited July 8, 2009 by slipperybits

[Husky]

Jim,

You asked about user friendly. JMHO, RTV silicone is the most user friendly of the items you mentioned.

Do you have pics of what you want to make molds of?

[slipperybits]

Husky, I read your post thoroughly before posting here. Just wasn't sure about the suitability of the 100% silicone for 2-part moulds and where i would find the right type of silicone.

Well, here are a few examples of the TYPES of lures i would like to replicate. Not these exact lures - because that would probably be illegal right...

Once I get the hang of it I'm sure i will begin to expand my repotoire of baits, grubs and worms etc.

Right now i am in need of some 4-5" jerk and swim baits to feed the ravenous 5-20KG snapper currently marauding the inshore reefs.

Still confused about which way to go with the medium

Polyester Resin, Polyeurethane resin, bondo/resin mix, RTV, POP, water putty, 100% pourable silicone

JUST DON'T KNOW!

Edited July 8, 2009 by slipperybits

[gone2long]

Here's what I use:

http://images.orgill.com/200x200/1421098.jpg

Bondo makes many different types of fillers but fiberglass resin is not a filler but more like an adhesivefiller used in conjunction with fiberglass matte, I personally didn't know they were using it for automotive uses until I read it on this site. I'm not sure if anybody is using the Bondo body filler, I would think its to thick but I may be wrong I haven't had any contact with that stuff since the early 80's. And to clear things up the resin is not fiberglass but polyester, the reason its called fiberglass resin is because its used in conjunction with fiberglass matte.

RTV:POP:

FIBERGLASS RESIN:

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Hope this clears things up for ya.

Ya know I only paid $54.00 for this 6" fluke mold:

http://www.del-mart.com/shop/files/thumbnails/t_16461.jpg

I use the resin straight out of the can mixed with only the hardener.

The paper clip protrudes from what ever end is opposite the pour end, and yes it has to protrude in order for air to escape just sand the end of your mold down until the aiway opens up.

Make a pour hole by rolling up a wad of clay, if you look at a pic of a aluminum 2 piece mold you'l get the idea.

Chris

Edited July 8, 2009 by mrbilky
Additions

[Husky]

The Paddle Tail bait molds would do well in a poured RTV mold. Also, consider that Resins build up high amounts of heat as they cure so there's an excellent chance your soft model will get cooked between the heat, chemicals and the severe undercuts inherent with the Paddle Tail. Bondo Resin Stinks to high heaven, BTW. I may be biased, but RTV is simple, efficient, inexpensive if used prudently, and VERY FORGIVING.

MHO, Make 1 RTV mold, Make a Mother Mold of that out of POP and knock out more RTV molds from that, easily.Plus with a POP mother Mold, you could pack the less expensive Silicone Sealer Silicone/Water mix in it, for subsequent molds!

Check for Suppliers Down Under. There must be someone local. If not, consider becoming a distributor!!!

Edited July 8, 2009 by Husky

[gone2long]

Oh and I forgot to mention I make my mold forms from LEGO's works great and very adjustable.

[slipperybits]

Interesting Point Husky,

Hey Mr Bilky, u ever have any trouble with heat affecting the SP masters during curing?

Yeh, the Fluke molds are ONLY $50-$80, but you only get 1 style in 1 size. Plus, I have to tack on another $30-$40 for shipping to Aus...

So, money being a consideration - I think the DIY approach is the way to go. When you say make a mother mould out of POP, I assume you mean a POP hard copy of the actual bait right Husky?

Is this necessary when using the pourable water/silicone. Can you not use the soft bait master with this medium?

Just wondering exactly what is meant by undercuts. The paddle-tails have thin and fat sections - yes, but how would they would create a problem coming out of the mould.

Also. If you look closely at the Powerbaits (middle pic), they have a fine split tail. Do you think this would create a problem for creating moulds?

Also wondering about the shrinkage factor of fg resin. Might it lock the baits in as it contracts during curing?

Finally, what sort of quantity of RTV or resin should i be looking at to make a few different types of moulds (factoring in that I will probably make a few mistakes).

What is the best type of recepticle to pour the baits into - obviously something with good release properties and something flexible to enable the bait to be worked out like an ice cream container. But also something small to minimise RTV or Resin waste... What do people generally use?

So many questions, appreciate the help though. I'm definately learning.... slowly.

Edited July 9, 2009 by slipperybits

[Big Pancho]

Jim here is my two cents Chris explained the main four materials in order to make the molds. Bondo (auto body filler) FGR (Fiber Glass Resin) RTV (Room Temperature Silicone) POP (Plaster Of Paris)

Jim my choice to start with will be POP this is keep the cost down until you get the hang of things. After your POP molds are made pour your baits and see how they work. The next step will be in the testing of the bait to see how they swim. There will be modifications to make at first in order to get your baits to swim true. This can get frustrating at times but hang in there it will work out in the end. I myself have made many baits that just did not work out. I have made only one piece mold and have not tried to make the two piece mold yet. Start with the one piece mold and work your way up. After you have a good bait or baits this is when you can step it up and make the silicone molds. Silicone is very pricey at $130.00 dollars for a one gallon can. Silicone by far is the best material to use to make the molds. No release agent is necessary when pouring your baits. Pour the plastic let it set up and pull the bait right out of the mold. Very easy and the bait come out nice.

There is some really cool stuff on YOUTUBE. Type in two piece molds and they will show you step by step on how to do it. There is a guy making a silicone mold of a toy tree very informative. I think in order to make the two piece mold you will have to start with a hard mold of your bait in order to set half of the bait in clay; pour the mold material. Insert dowls in the first half of the mold on all four corners. Let this half cure. Than remove the dowls from the first half of the cured mold next mix the second half of the mold material and pour the second half. You will have to drill a top pour hole on the second half of the mold in order to pour the plastic in once you have poured the first half or bottom of your bait. It will take some time to learn when to pour different colors on top of each other. This is just trial and error. If you wait to long you will get cold cracks between layers. Stick to solid colors or two color at first and work your way into the other layers. This is a very fun hobby but it can get very addicting after awhile. Take you time and have fun making them. I will do my best to help with your questions.

Frank

Edited July 9, 2009 by Big Pancho

[Frank]

OK Let me fill you in on bondo. That is a trade name for the dynatron corp. The product is a polyester resin with a talc for filler and a kind of grey color. Now that is out of the way let me explain what you see on some sights as for the pictures. I will call these products bondo for the time being. Bondo has a hardener that has a color so you know when it is mixed well. It comes in two basic colors red&blue. Thus the pink you have seen. The ratio is about 100 to 1 bondo to hardener.

It is basically used for auto body purposes to fill and level body panels. It should be available at a automotive paint store.

Now the advanced version. Now i will call these products fillers but they are the same basic products except for the resin is mixed with microspheres. This makes it lighter and easy to sand, not that this matters. These products cost more but the end product is smoother in apperrance. Now these products are some times yellw in color because of chemicals that help them stick to metal better. Not an issue in this case but for some reason the hardener is blue in most cases thus you get a green finish color.Still no problem. Now with these they sell a thinner that is nothing more than a polyester resin that you can add to the filler to make it runnier/smoother. When you use these together you can make some pretty intricut molds.

The cost here in US is about $60 for 8lbs, about a gallon.The thinner is about $16 a pint.

You can make your own filler with polyester resin and micsospheres but you have to stir for days it seems like.

Hope this helps the confusion on bondo/filler.

Buy the way it sets up in about five minutes and can be used when it cools down,about 20 min.If you make a two piece mold you will need to use mold release agent or you will have a mess.

[Big Pancho]

Jim here is my two cents Chris explained the main four materials in order to make the molds. Bondo (auto body filler) FGR (Fiber Glass Resin) RTV (Room Temperature Silicone) POP (Plaster Of Paris)

Jim my choice to start with will be POP this is keep the cost down until you get the hang of things. After your POP molds are made pour your baits and see how they work. The next step will be in the testing of the bait to see how they swim. There will be modifications to make at first in order to get your baits to swim true. This can get frustrating at times but hang in there it will work out in the end. I myself have made many baits that just did not work out. I have made only one piece mold and have not tried to make the two piece mold yet. Start with the one piece mold and work your way up. There is some really cool stuff on YOUTUBE. Type in two piece molds and they will show you step by step on how to do it. There is a guy making a silicone mold of a toy tree very informative. I think in order to make the two piece mold you will have to start with a hard mold of your bait in order to set half of the bait in clay; pour the mold material. Insert dowls in the first half of the mold on all four corners. Let this half cure. Than remove the dowls from the first half of the cured mold next mix the second half of the mold material and pour the second half. You will have to drill a top pour hole on the second half of the mold in order to pour the plastic in once you have poured the first half or bottom of your bait. It will take some time to learn when to pour different colors on top of each other. This is just trial and error. If you wait to long you will get cold cracks between layers. Stick to solid colors or two color at first and work your way into the other layers. This is a very fun hobby but it can get very addicting after awhile. Take you time and have fun making them. I will do my best to help with your questions. Check out these two sites there is a two piece molds and will give you an idea on how it is set up.

I took a 98 'cause I never liked a limo...

Frank

Edited July 9, 2009 by Big Pancho

[Husky]

Interesting Point Husky,

So, money being a consideration - I think the DIY approach is the way to go. When you say make a mother mould out of POP, I assume you mean a POP hard copy of the actual bait right Husky?

No, you'll make a reverse copy of the RTV mold. Place the RTV mold in a mild boc with clearace on all sides ab above. Place the mold into the box , cavity facing up, and pour the Plaster over it, taking care to get a complete fill. When it has set, you can pour RTV into it and make more molds, without having to lay them up.

Here's a quick anf Easy mold box which you cab tailor to the exact size you need.

Is this necessary when using the pourable water/silicone. Can you not use the soft bait master with this medium?

You use a soft bait as a master, providing it doesny have appendages i.e. Paddle tails. I did make some molds with this method with soft models.

Just wondering exactly what is meant by undercuts. The paddle-tails have thin and fat sections - yes, but how would they would create a problem coming out of the mould.

Undercuts mean a section of the model that is covered with and "locked" into the mold due to being larger than the part of the cavity it will have ti go through to exit the mold. With soft plastic casting, you can get away with it to some extent due to the very maliable nature of the plastic. Still, in hard, one piece molds, extreme care and diligence must be used when removing lures with paddle tails etc. They have to be "coaxed out", or the will break off.

Also. If you look closely at the Powerbaits (middle pic), they have a fine split tail. Do you think this would create a problem for creating moulds?

If you have the model TOTALLY affixed to the flat surface, it should catch all the details, but I haven't tried that type of bait with this process. Perhaps someone else here has, though.

Finally, what sort of quantity of RTV or resin should i be looking at to make a few different types of moulds (factoring in that I will probably make a few mistakes).

Most commercial mold I've see, use way too much RTV. They probably get it in 55 gal drums and have a much lower cost than us, so it's not a major factor. Basically you just need enough to cover the model and have 1/4" clearance all around. More than that is overkill. It takes 20 gms of RTV to fill 1 cubic inch.

For Example if your model is 4.5" ling and 3/8" wide and high, you coud make a box 5" L x 7/8" W and 7/8" high to make a sturdy RTV mold. A mold that size would appx. 76gms of silicone, excluding the area the model occupies. A pound is 454 gms, so you shold be able to get 6 molds from a pound of RTV. IOW, at retail cost for a 2lb kit, here in the U.S., a mold like that would cost me $2.50.

What is the best type of recepticle to pour the baits into - obviously something with good release properties and something flexible to enable the bait to be worked out like an ice cream container. But also something small to minimise RTV or Resin waste... What do people generally use?

So many questions, appreciate the help though. I'm definately learning.... slowly.

Good Luck and have fun. FWIW, Practice with the POP as per Pancho's suggestion.

Edited July 9, 2009 by Husky

[zook2001]

The equivalent product in would be Plastibond or plain old auto-filler available in a variety of brands.If one wanted to delve into your own mix of talc, microspheres etc then your local Whitworths or Bias Boating store will help you out.

OK Let me fill you in on bondo. That is a trade name for the dynatron corp. The product is a polyester resin with a talc for filler and a kind of grey color. Now that is out of the way let me explain what you see on some sights as for the pictures. I will call these products bondo for the time being. Bondo has a hardener that has a color so you know when it is mixed well. It comes in two basic colors red&blue. Thus the pink you have seen. The ratio is about 100 to 1 bondo to hardener.

It is basically used for auto body purposes to fill and level body panels. It should be available at a automotive paint store.

Now the advanced version. Now i will call these products fillers but they are the same basic products except for the resin is mixed with microspheres. This makes it lighter and easy to sand, not that this matters. These products cost more but the end product is smoother in apperrance. Now these products are some times yellw in color because of chemicals that help them stick to metal better. Not an issue in this case but for some reason the hardener is blue in most cases thus you get a green finish color.Still no problem. Now with these they sell a thinner that is nothing more than a polyester resin that you can add to the filler to make it runnier/smoother. When you use these together you can make some pretty intricut molds.

The cost here in US is about $60 for 8lbs, about a gallon.The thinner is about $16 a pint.

You can make your own filler with polyester resin and micsospheres but you have to stir for days it seems like.

Hope this helps the confusion on bondo/filler.

Buy the way it sets up in about five minutes and can be used when it cools down,about 20 min.If you make a two piece mold you will need to use mold release agent or you will have a mess.