Question about resin use

[Bizarro Lois]

I was using some Smooth-On I had around the house to make little accessories. I frequently have trouble with the lids sticking on the jars, even though I wipe off both the lid and the edge of the jar before I close them. First question is, is there anything I can do to stop the lids from sticking? I don't know if there's a way to lubricate it, or if some of the chemical is rising up and jamming it shut. Is there a time frame in which the resin has to be used in order to prevent this?
The second part of my problem is that the last time I used the resin, I struggled to get it open. I didn't notice it right away, but now the lid of the yellow container is cracked. There is a thick crust, and I can hear liquid sloshing around underneath. Did some kind of separation take place, or is the stuff underneath still good? I was able to pour a little bit of the liquid out and used an equal amount from the blue container in a small mold, just to see if it hardens. It's not looking good right now, but I'll check on it later and post if there's any change. If I break apart the crust, is there any chance it will mix back in with the liquid and be useable? It's a pain in the butt because there was quite a bit left of both chemicals. Is there anything else I could mix with the blue jar that would work the same way, so I don't have to waste it? I don't think Smooth On sells the resin and hardener separately.

 

[exoray]

First question is, is there anything I can do to stop the lids from sticking?

In addition to the wiping you are doing, you can do a final wipe with a fresh towel lightly soaked in acetone, and then displace the remaining air in the jar/bottle/jub with a nitrogen (other other inert gas) prior to capping it back up... The crusties are a result of oxygen contamination... Smooth on sells a blanket gas, and most fine wine stores also carry a blanket gas designed for wine but will work for the resin as well...

I don't know if there's a way to lubricate it, or if some of the chemical is rising up and jamming it shut.

After cleaning and before capping you could take a very small amount of Vaseline and give it an ever so thin coating, but I would say this is overkill...

Is there a time frame in which the resin has to be used in order to prevent this?

As soon as possible, shelf life isn't that long once oxygen hits it... I'm not saying it all the sudden stops working, but as the weeks tick by it is losing it's shelf life and issues can arise... I would say properly stored in a cool environment, sealed tightly with a nitrogen blanket you will get several months without any noticeable issues... Beyond that you are rolling the dice, I have had resin work fine after 6 months on the shelf, and I have had it totally go wonky after 1 month... Different brands and different formulas also store better then others...

The second part of my problem is that the last time I used the resin, I struggled to get it open. I didn't notice it right away, but now the lid of the yellow container is cracked. There is a thick crust, and I can hear liquid sloshing around underneath. Did some kind of separation take place, or is the stuff underneath still good?

Oxygen contamination, the stuff under the crust 'might' still be good as the crust creates a barrier, but I HIGHLY recommend you test first! Filter the remaining liquid through a junk T-Shirt to make sure all the crusties are removed before use... You likely have water contamination as well at this point so it might foam up when curing, some resins more then others...

I was able to pour a little bit of the liquid out and used an equal amount from the blue container in a small mold, just to see if it hardens. It's not looking good right now, but I'll check on it later and post if there's any change.

Did you stir or shake it well? Many resins separate a little after sitting for an extend period of time...

If I break apart the crust, is there any chance it will mix back in with the liquid and be useable?

No discard the crust...

It's a pain in the butt because there was quite a bit left of both chemicals. Is there anything else I could mix with the blue jar that would work the same way, so I don't have to waste it? I don't think Smooth On sells the resin and hardener separately.

If you can't get it working based on what I said above, it's time to call it a lose and get some new resin...

 

[Bizarro Lois]

Oxygen contamination, the stuff under the crust 'might' still be good as the crust creates a barrier, but I HIGHLY recommend you test first! Filter the remaining liquid through a junk T-Shirt to make sure all the crusties are removed before use... You likely have water contamination as well at this point so it might foam up when curing, some resins more then others...

Did you stir or shake it well? Many resins separate a little after sitting for an extend period of time...

No discard the crust...

If you can't get it working based on what I said above, it's time to call it a lose and get some new resin...

I shook it as well as I could, but the crust was pretty thick and covered the whole surface. I broke it apart and will try to filter it out.

 

[Mockle]

, I struggled to get it open. .

I have the same problem no matter what I do... So I use visegrips opens every time lol

 

[Bizarro Lois]

Well, the first mold I poured didn't even attempt to set. I'll try again after I have a chance to filter and mix the yellow container thoroughly.

 

[JPolacchi]

Well,if it isn't setting you either have the mix ratio wrong or there is something wrong with the resin itself.Unless it is really cold(like 60 degrees or colder),that can mess with the resin setting also.Maybe it is too old or it got contaminated somehow?Does it mix by weight or volume?

 

[Bizarro Lois]

Well,if it isn't setting you either have the mix ratio wrong or there is something wrong with the resin itself.Unless it is really cold(like 60 degrees or colder),that can mess with the resin setting also.Maybe it is too old or it got contaminated somehow?Does it mix by weight or volume?

It's a 1:1 mix, so I didn't get the ratio wrong. I already know what's wrong with it(see first post), I was just asking if I can prevent some of it happening to other bottles, and if what I have is still usable.

 

[JPolacchi]

Sorry about that.I'd say the resin is old.As far as keepiong it from doing what its doing,there is a preservative you can spray into the resin to extend its shelf life.The lids..well...I think someone mentioned cleaning the threads off the lid&bottle real well with a clean reag,then using another clean rag w/some acetone to clean the threads reall well to not only keep it from sticking, but so that you can tightly seal the containers again to avoid an humidity getting inside.Urethane resin is very moisture sensitive.There is still the possibility that the resin is contaminated or defetcive either due to its shelf life expiring or some other reason.I'd contact Smooth-On.

 

[Mostly Fantasy]

You can try a layer of masking tape on the (male) threads when you take the cap off the first time- a shot of nitrogen will blanket the resin and prevent air from crusting it up. Vaseline on top of the tape also helps. What's underneath is probably still good, but might need filtering to get rid of any chunks.

 

[Bizarro Lois]

Maybe if I shake it well after filtering. So is the nitrogen in little packs, like a Guiness can?

 

[Wes R]

I know that the brand i got from micromark had a 1 year shelf life but it seems to lose strength after 6 months. I give it a good shake before pouring and let it sit so the bubbles work out too.

 

[exoray]

So is the nitrogen in little packs, like a Guiness can?

No, if you purchase it over the counter for consumers, it will be it little bottle just like the air duster bottles for computers and such... You would squirt some in the bottle before capping it up creating a blanket of nitrogen that keeps the air away... Most of the commercial preservatives likely have other gases in them that are heavier and fall lower creating a better blanket...

For me I'm going to some day get my Argon tank setup for this, I have the tank, and it's full of Argon just been too lazy to get the regulator and rig up something... This thread has made me pick up the project again, just need to dig around for a cheap regulator and some hose...

 

[danbakeronline]

Exoray is right on all points there. I'm assuming you're using SmoothCast 300, and once it's been opened, the raw materials only have a shelf life of 9-12 months.