foam beginner's questions...
26 replies to this topic
Posted 12 January 2006 - 11:48 AM
i'm thinking of starting making some lures in foam and have done a search on the forum and looked at the tutorials. however i've still got a couple of questions which i'd like to pose to the foam experts-
1. how well does foam reproduce detail? does the lure have to be smooth or can there be carved mouth/gills or scale texture? my worry is that the foam will flake/break or get stuck to the mould.
2. can 16lb foam hold a screw in eye securely? anyone tried this for heavy duty baits for musky and pike? or perhaps someone has done a pull test?
3. whats the best mould material? is there a something cheaper than RTV silicone? any experience casting foam into moldmax or other smooth-on rubbers?
4. any other advice greatly appreciated.
Posted 12 January 2006 - 05:13 PM
I can help out on some of the questions.
1. Carved mouth and details are fine as long as you don't create a mold that will cause the lure to "lock" itself. Essentially nothing can create an undercut. I have never had foam break or flake. I have weighted too long to demold and had to force it out. Silicone most likely will be more forgiving but I still use the low tech stuff.
2. I only use through wire construction on my foamies. I recall some have set screw eyes with devcon with no problems. I just find for about the same amount of effort (maybe less) I can bend a through wire harness.
3. I have used Durhams Rock Puddy but mainly bondo to create my molds. Haven't ventured into the RTV although that is probably the best way to go. I will most likely try it out soon.
4. Take time making the mold and don't rush things. Venting is often needed to eliminate air pockets in some areas. Coating the mold in these difficult areas (like recessed sockets for eyes) before filling the one half, reduces blemishes a lot. I find vasoline brushed on straight with a child's paint brush works easily for a demolding agent. In my experience the most frustrating thing about foamies is the surface prep time needed to get a surface ready for paint.
Posted 13 January 2006 - 06:09 AM
Thanks for the generous advice!
i can't wait to give it a go.
will post pictures when i do manage to make the baits!
Posted 13 January 2006 - 07:38 AM
Only buy as much foam as you'll use in a 3 week period as that is appx the shelf life of opened foam. After that, it begins to lose its' properties. Please Don't ask how I found that out.
Posted 13 January 2006 - 02:07 PM
foam will cast and release from RTV no problem. Do not use any petrolium products as release agents with RTV it will deteriorate your molds quickly.
The 3 lures in the pic are from RTV molds. The pink one is a 5lb foam test for details. Came out great.
5lb is too weak. I've tried 15lb foam-it since. The 15lb also picks up the details and releases just fine however it has a stronger expansion and will push more on the mold walls.
RTV is very supple and will distort if clamped too tightly. I'd recommend a mold support that you can clamp tight that wont distort the mold. Make the side supports a little shorter than the mold so it will seal the mold tightly. Also use an RTV with a high shore hardness. I've used moldmax 30 and still get some seamline flash. I think MM40 with the wood support shell will work better though I've not tried it yet. The support shell will help clamp the mold evenly and keep the blank in form without distortion.
Posted 13 January 2006 - 03:04 PM
Shawn, did you escape or did someone pay he ransom?
It looks as if the foam is serving your needs, well.
Posted 14 January 2006 - 01:22 AM
LOL Husky I'm shakin it boss! I'm shakin it! Workin a proto and preppin mold boxes here.
I'm getting the idea that salmo could possibly be using aluminum molds that are bolted shut on hydruallic presses and using corn starch as a release agent. The presses would pull evenly while demolding and cornstarch protects the aluminum.
I've got RTV to pour and will try the support shells on this batch of molds. I've also got "pharmacutical grade corn starch" to try in the molds. It's very fine and sticks to smooth surfaces. Currently setting up a table with enough molds and harnesses to pour a full kit of featherlite ina day and will compare both in a side by side RTV mold test.
They are 16 gauge brass wire harnesses. I use a nail jig to tie them. Would I trust an eyescrew in foam? Yes and no... for bass and pike lures yes. The foam is made up of chemicals similar to epoxy glue and will bond well with the screw.
For larger game fish like stripers and musky the screw alone might not be enough. A makeshift flat washer on the screw could work as a strong anchor that should be tuff enough.
Posted 15 January 2006 - 11:20 PM
Hi,I made my mold whit mold max 40 but dident tryed it yet,the wood sheel is a good idea!!I will do that before molding some!
I am sending a pic of me mold.Cheers.muskydan666
Posted 17 January 2006 - 12:36 PM
Glad to hear that we have another foamie guy here
Yes, salmo definitely are using aluminum molds. But I do not understand what do you mean by "corn starch"? I think if aluminum mold is polished enough, they could be used without release agent, because foam do not stick to glass-smooth surfaces
Shawn, you should try polyester fiberglass resin instead of RTV. You can put this mold in to the press, so seamline flash is very minimal
Posted 17 January 2006 - 12:56 PM
here is the photo of seamline I am getting from fiberglass resin mold:
Posted 17 January 2006 - 01:33 PM
Hy there vytautas! U mean just the resin used for fiberglass, or with the fibers as well?
I just procured some resin, and that's why i ask. I'm trying for some days to find a RTV source here in my country, but with no results for now. So i have to try some alternative materials until that time comes. Even though i wouldn't want to try the car kit stuff. I want to be sure i will be able to demold heavily detailed baits
Posted 17 January 2006 - 02:28 PM
I use resin only, bought it from car tuning company. It is very similar to this one used here:
smells like hell, not very friendly to some plastics, but works fine for me
Yeaa, here in Ltihuania there is also difficulties finding stuff like this. Try this source for RTV and foams: www.kaupo.de - they are very helpful guys
Posted 17 January 2006 - 03:12 PM
I'll be looking for some time for a RTV source arround here. That's a last resource. How does the demolding go vith those molds
Posted 17 January 2006 - 03:39 PM
Outstanding seamline Vy. The foam cells look like they are fully closed. Corn starch has many uses. It's starch extracted from corn. It has the consistency of baking flour but is sticky. It's used in push molds as a release agent as it sticks well to a smooth surface but releases to the castings. It could aid the foam to form a good skin and release better from the aluminum. You might want to try it in your poly molds.
That's a great mold. I noticed you left out harness mounts. Is that to use screws instead of a thru wire? If so what size screws you using? Sweet lookin bait. Post pics when you get a few cast.
Posted 20 January 2006 - 11:38 PM
Hi Shawn,No my harness mounts are not a side!!!It's juste that i made them a little different then yours!I made them whit some little anchor usuly used to hold shelf(ikea style)el chipo!!!ina tv furniture!!! :-D
Cheers and thank's for your nice tutorial on mold making,It help me a lot to make my first mold!!!
Posted 21 January 2006 - 07:13 PM
Glad the tutorial came in handy That's cool using shelf mounts. Let us know how your first casts come out and show off them lures!
Posted 21 January 2006 - 08:15 PM
Hi Shawn,I made my first cast today! Not very nice!!the mold Plaster of Paris open a few seconds after pouring!! but the second one is very nice,a few bubbles but nothing to worry about!! I'm sending some pics of the lure!!
Posted 21 January 2006 - 09:15 PM
You've got to be drunk with power right about now LOL :grin: It's a great feelin that first batch of lures .
Did you make a box support for clamping the mold? Was there any "flash" on the seamline?