early RTV results

[dtrs5kprs]

Just poured 6 molds using 2 of the new RTV's I ordered recently from Smooth-On.

Poured 2 with Mold Max 27T, a translucent tin-cure silicone, and the other 4 with Smooth Sil 30, a platinum-cure silicone. Both are 10:1 mix by weight (or volume + class A eyeball). Of the 2, I am happier initially with the ease of use and pouring of the Smooth Sil. It mixes and handles similarly to the RTV from LC or Barlows. The Mold Max looks like it really needs to be degassed, lots of bubbles, but it is still early.

Will post a follow-up when the molds have cured. Also have some of the Smooth Sil 920, a 1:1 product, and some Mold Max 15 (lower or softer shore hardness) to play with.

Rough prices...$80/10# kit of Mold Max, $115/10# kit of Smooth Sil.

[robbor]

Any idea mow many molds you think you can make per 10# kit??? I like the class A eyeball!!

[dtrs5kprs]

Most of the molds I make end up somewhere between 100cc and 300cc of mixed RTV, regardless of the type of RTV. That is for molds like a 4-5 cavity chunk mold, 2 cavity beaver mold, 4-6 cavity finesse mold, etc.

To get a rough estimate...the 10# LC kit is packed in a gallon jug, at more or less 3785cc per gallon. If you use 200cc as an average mold volume, you are looking at about 18 or so molds. You can do a lot to minimize waste by spending a good amount of time planning and setting up your molds.

Update on molds: The Mold Max 27T is setting up better than I expected. Surface bubbles on what will be the botom of the mold are not as problematic as they might have been, waiting to see what the cavities look like. Used soft mold forms so they will take a bit longer than 24 hours to completely cure.

[dtrs5kprs]

Update on molds 3/11/06:

Well...the Mold Max 27T molds (tin cure silicone, translucent) cured and set up just fine. This was the material I expected not to work due to initial bubbles. A quick rough test pour was a success...nice pour, nice de-mold, nice baits.

Surprisingly, the SmoothSil 930 (platinum cure silicone, blue) didn't work worth a sh*t. Total cure failure on any surfaces exposed to the soft plastic. This is the most significant setback I have had with any RTV, and the first time I have seen it fail to cure. Will try it on some hard molds (silicone safe clay proto's, hard plastic mold boxes).

Will re-try and post some pics when time allows. Failure = increased motivation to succeed.

[dtrs5kprs]

Pics of RTV molds:

1) Dark blue mold at left (craw 2 cavity) is made from Smooth On SoothSil 930 platinum cure silicone. This is the silicone that failed to cure when poured over soft bait masters. It cured nicely (although I may have gone a bit overboard with the activator, judging by color) when poured on and over a hard master (plastic resin "mother", mold box, replicator box, whatever you name it). In this case, the resin master was prepared from 2 part liquid plastic (Smooth On 300 series) and had been lacquer coated with a clear spray lacquer.

Mold cured overnight, has nice shiny cavities, and demolded from the master with a tug at both ends. This RTV, or one of the same line with a higher shore hardness, might have some applications for lead molding or foamie crankbait molding. Seems a much tougher material.

2) The clear mold at top is made from Smooth On Mold Max 27T. It was made over a soft master of an aluminum mold (see my post from spring 2005 for process). This is one of the molds that caused concern due to what seemed an excess of bubbles when poured and while curing. The cavities cured nicely and seem to be unaffected by the bubbles. I still think this product would be easier to use if de-gassed.

After pouring about 60 or so baits the 27T molds produce a nice bait with adequate detail. **Only negative, and it is a big one, is the transparency of the material. It makes it very difficult to see cavity detail when pouring, esp under a Lee pot. This might not be such an issue with a "straight" mold like a worm, fry, reaper, etc. Cost is good, in the neighborhood of $80/10# or so.

3) The light blue mold at bottom middle, is made from TinSil 70-25 from US Composites. Previously I had some issues with bubbles, cure, and set-up with this material, but am now attributing those to operator error. When poured over a soft master (same type as the Mold Max 27T) it produced a mold with many of the same characteristics as the Lure Craft RTV yields. The mold has excellent detail, sharp edges, and is quite a bit more flexible than LC RTV or either of the Smooth On products used to date. Cost is similar to the SmoothSil 930...about $110/gallon (9 or so pounds).

4) The slightly darker, used looking mold, at right is made from LC RTV over the same master, and is included for comparison. Cost $240/gallon or so. A good and forgiving product in most of my experiences.

All the beaver molds were made as 2 cavities, then cut down the middle for ease of use. Just an explanation of the rough edges.

[CrawChuck]

Nice looking molds!

[earthworm77]

I've been using Micro Mark 1 to 1 ratio and it works like a dream!

[jm]

After pouring about 60 or so baits the 27T molds produce a nice bait with adequate detail. **Only negative, and it is a big one, is the transparency of the material.

I wonder if the translucent product could be colored? That would make it a product that is easy to use, relatively inexpensive, good quality, and even the preferred color.

[robbor]

Im shure everyone here appreciates you spending the time to post this info, thanks dtrs5kprs. Nice looking molds, they all look like they have good detail except the craw which im shure didnt have the detail to start with. Why split them? to me it would seem simpler to have 2-3 per mold unless you are making molds for others.

[millsryno]

Nice pics. The detail and quality of those look to be as good as aluminum. Can you tell any difference between the finished product?

[dtrs5kprs]

A few answers:

1) Detail is very good with all of the materials used. The beaver molds show the detail that can be acheived, the craw is a smooth finish bait.

2) I split the beaver molds because I found them too wide to conveniently pour using Lee pots when they were a 2 cavity mold. I pour using drywall tape knives to hold and position the molds under the pour spout (keeps what is left of my fingers away from the hot goo). As a 2 cavity mold it was difficult to position the mold without bending into strange angles...a problem if you have 10 or so molds lined up and 2 to 3 pots running side by side. When split, I can line two single cavities up nose to tail on the tape knife and let it rip.

3) Smooth On has info on coloring their RTV. I was going to paint the cavities on a couple of the molds with some dark worm dye and see if that would work.

4) The only difference I can tell between the aluminum original and the RTV version is that the aluminum mold tends to produce a little thicker bait. I don't think this is the result of shrinkage when molding. It seems like the plastic, maybe due to faster cooling, sort of pools up a bit more in the metal mold.