Does anyone else cast their own parts?

One the 1st questions I asked from a supply source of resin when I was getting started about 10 years ago -- what's the shelf life.

Response was that the shelf life of these materials after opening a sealed bottle is ~6 months.  Unless you can truly seal these materials under an inert gas atmosphere, once open, use them.

I have yet to need any resin with a longer than 6 min working time to eliminate bubbles.  I have considered buying some that has a 20 min working time if that became a real problem,  Just have not had the need.  When bubbles tend to be a problem, I have found that it is invariable my own user error with the mold and how I put the resin into the mold, how much and how I distribute it are factors that I have ignored.  I have learned that oft times the careful addition of "just enough" to "paint" the surfaces of the mold, to add the resin in portions, to "inject" the resin into cavities with a transfer pipette, etc. I have at times made use of the clothes drier as a working platform to make use of the vibrations to aid in bubble release.  I have yet to need a vacuum chamber.

MWB, do you think filling the bottle with nitrogen would help extend shelf life? No problem for me doing that.

Pete

Pete,

I've used Oomoo30 in the past when I was into1/6 scale military stuff.  A local place carries it and I bought some from them that was solid when I opened it.  Seems like I took it back and got another, can't recall now.

But that was the only time, all others have been fine and it's a good product.

Smooth-On comes out with new stuff all the time and I need to look at their new products.  I haven't used any in 4-5 years.

Next time I buy I'm going to see if there's any kind of expiration or use by date on the can/bottle before I buy or order.

Here's their blurb on shelf-life:

http://www.smooth-on.com/faq_d...?faq_id=32&cID=4

Sounds like 6 months to 1 year is our best bet. I think I've still got some in the garage, I'll check this afternoon after I get home from work.

Thanks for the link Bob. I should have read that first. I think mine was useful for at least two years so I can't complain. I ordered some more of the same because I liked the results but an open to alternatives when this one gives up the ghost. In the meantime I guess I need to come up with some more projects, fast.

Pete

Norton posted:

MWB, do you think filling the bottle with nitrogen would help extend shelf life? No problem for me doing that.

Pete

That's a firm "maybe" and a firm "can't hurt".  The real question is whether you can really seal the bottle airtight.

I very rarely store resin casting supplies once open for more than a few weeks.  I try very hard to have enough work and molds lined up so as to consume it all with minimal waste.  Whatever it is I'm making, I make a lot of them for me or whoever, and then I have on the side a host of additional detail part molds to capture every excess drop. 

Did you put part A & B caps on the wrong bottles?
Had casting bottles (part A & B) last over a year.
Maybe I was lucky

Ron, Who knows but I doubt it. I pour A in a beaker, put the cap back on and then open the second bottle. I am pretty sure mine lasted well over a year but I think, looking back at what I made with this stuff, its well over 5 years old. The whole bottle had kicked so I don't think residue on the cap would have been enough to cure it.

Pete

Smooth On recommends to use the unopened silicone ( Mold Max 30 ) in 6 months .

Check out Reynolds Advanced materials...they carry all of the Smooth on products and some...this place is directly geared towards casting/molds/etc....

This is a list of what I typically use:

1. Oomo 25 (tin cure silicone rubber) for molds

2. Smoothcast 300Q and 300 (the "Q" version sets and is ready for demold in a minute or so)

3. Ease release 200 (spray release applied to "master" prior to silicone application)

*The reason I researched and got into this was that I was tired of building the same thing over and over from scratch (abutments, stone walls, etc.) and instead of spending all that time creating each piece (that might have or have not been an exact replica of the previously completed one)..I decided to spend some decent time creating one "master" and then making a mold of it...and then reproducing as many as I wanted...in minutes. Time = money...and it's money well spent.

Anyone here ever cast any parts that took stress from resin? I have a frame I am looking to cast, to replace a rotting wooden one, and want to know that it will take stress before I do so.

I have 2 steam engines that are resin castings - sold off the 3rd one.  Done correctly with quality resin, there's no reason why this will not be stable.

Having some pictures of what you are looking to get made or make would be helpful.