|
|
Post by vsotto on Aug 24, 2020 12:09:00 GMT -5
It has been a couple of months since I've created any molds, and this morning, I mixed up a batch of HS3 to pour over my masters. It the past, it has always poured very thinly and leveled very nicely. However, today it started to cure extremely fast. It started getting sticky and clumpy even while I was mixing it in the mixing cup - nothing like when I last used it. I mixed it in my basement, with temps in the 70's and normal feeling humidity. It's been about two hours since I poured it into the molds and looks to be completely cured. I haven't pulled out the masters, but I have low hopes for a successful mold.
Any ideas what might have caused this and what I can do to avoid this in the future? Could tiny amounts of water in the mixing cup cause it cure so quickly? I opened the container about 9 months ago and has been stored in dry basement. Is there anything else that might have caused it the problem?
Thanks for any advice.
|
|
|
|
Post by Brian on Aug 24, 2020 17:55:35 GMT -5
Questions.......hopefully get this issue resolved...
Just confirming that you have had successful mold pours from this batch aprox. 2 months ago and that the same container was first opened 9 months ago...correct?
How long did you mix it for before you noticed the sudden change in consistency
Did you mix by volume or by weight
What was the temperature of the masters...room temp. in the 70's, Hot, Cold etc. etc.
What was the condition of the mixing cups....wet,dry ....if wet was it water or some other liquid.
I've messed around with adding a couple grams extra catalyst to speed the curing process up, but nothing to this extent as far as cure time goes. As far as water goes, it would slow down the overall curing process if anything, but not the mix time as you would still have that short working time to deal with.
I'm curious to hear how the mold did turn out....if you can ,post some pictures, they may offer up some more clues as to what happened.
|
|
|
|
Post by vsotto on Aug 24, 2020 20:51:46 GMT -5
Brian, Thanks for the questions. I opened the package in November. I made a few small molds at that time. The last time mold I made was in January.
Everything was done in my basement. Air temp was mid-low 70's. Don't know about humidity, but we run a dehumidifier and it "felt" normal. Masters were ambient temp.
For this one, I estimated that I needed approx 200ml so I measured 200ml of tap water, transferred it to my mixing cup, made a mark at the height so I would know how much rubber to pour into the cup. Then I emptied the mixing cup and used a paper towel to dry the mixing cup. It is possible there were a couple drops still in the cup. I poured the rubber into the cup to my mark, on my digital scale. At this time, I got interupted for about 10 minutes and let it sit on the workbench (I had not added the catalyst yet). I then added the catalyst mixing 10:1 by weight and stirred.
I had done this a number of times already and felt pretty compfortible with the process and assumed I had a bunch of time. I stirred slowly using a wooden stick and at approx the two minute mark it started to feel very "thick". I began pouring into my mold and it started somewhat thick, and did not flow as was the case previously. By the time I was finished, I had to scoop it out of my mixing cup and put in the mold. It was the consistancy of sillyputty. I thought maybe it would self level over time. As evident in the first photo, it did not level. I put everything on a flat surface and placed them in the garage (as there is a discernable smell). This was probably 10-15 mins after initial mixing and the residual rubber in the mixing cup had already set. Outside temp was in the upper 80's today and quite humid.
I checked everything approx an hour after and the rubber seemed pretty solid. I waited until tonight (10 hours after pouring) and demolded. It seems to have set okay. However the rubber did not flow around all of the details and, there are large voids around and between the masters. But, frankly, it is much better than I expected. I'll have to create some resin castings to see how good it captured the detail of each individual piece. See photo 2.
I still have a small amount remaining in the container, and plan to put forms around the molds and pour more rubber to try to fill the voids. I figure I have nothing to loose at this point. I'll provide an update on what happens.
|
|
|
|
Post by Brian on Aug 26, 2020 22:35:39 GMT -5
....This one has me perplexed..........let us know if you come up with anything, particularly if you have the same issue with mixing a smaller batch for in filling the voids. I'll have to do some research on this end and if nothing else, recreate what you did to find out the cause since we know what the effect is.
|
|
|
|
Post by vsotto on Aug 27, 2020 8:15:00 GMT -5
As a follow up regarding this: I mixed up another small batch and tried to pour the silicon to fill the small voids in the fist mold. This time, I ensured to use an absolutely dry mixing cup. I mixed the silicon for about 2-3 minutes until it was fully mixed and then began to pour into the small voids. All seemed to be okay until about the 5 minute mark where the silicon mixture began to become thick and stringy consistancy. I had very mixed results filling the voids.
Since then I have poured some resin to test the molds, and there are a number of places where the silicon did no pick up the details of the originals or there are large voids around the masters. All-in-all, I think this was a failure. I will have the purchase some new silicone and create new molds.
|
|
|
|
Post by Willam Gross on Apr 7, 2021 10:31:01 GMT -5
It has been a couple of months since I've created any molds, and this morning, I mixed up a batch of HS3 to pour over my masters. It the past, it has always poured very thinly and leveled very nicely. However, today it started to cure extremely fast. It started getting sticky and clumpy even while I was mixing it in the mixing cup - nothing like when I last used it. I mixed it in my basement, with temps in the 70's and normal feeling humidity. It's been about two hours since I poured it into the molds and looks to be completely cured. I haven't pulled out the masters, but I have low hopes for a successful mold.
Any ideas what might have caused this and what I can do to avoid this in the future? Could tiny amounts of water in the mixing cup cause it cure so quickly? I opened the container about 9 months ago and has been stored in dry basement. Is there anything else that might have caused it the problem?
Thanks for any advice.
|
|
|
|
Post by Jen Flu on Aug 27, 2021 15:59:13 GMT -5
I know this is an old thread, but I just had this problem with a completely new box that the same issue - measured by weight, ambient temps in the high 70s. Everything was room temp, and I was using a new mixing cup/wood stick. It started getting firm in a matter of minutes, and was unusable within minutes after that.
|
|
|
|
Post by Brian on Aug 27, 2021 18:31:20 GMT -5
Sounds like you got a hold of a box that has the catalyst that has presented issues..... Please give Carol at Alumilite a call at 1 800 447 9344 (M-F reg bus. hrs.) reference this issue.....let her know that I have been corresponding with you on this.
|
|
|
|
Post by Nick on Sept 18, 2021 17:18:34 GMT -5
Mine wasn't quite as bad but I did experience similar results last night. New/clean mixing container and stir stick. Measured by volume. Stirred for around 2 minutes and then immediately poured into 2 small mold boxes (2" square). Right off the bat it was thick enough I could fold it over itself while pouring. By the 2nd box I had to use the stick to scrape it all out. I managed to avoid any air bubbles on the pieces I was making molds of and while the overall finish is nice I did loose some of the definition on smallet details. Demolded after only 4 hours. At that time a metal scraper wouldn't alter anything about the material and I could get very nice, clean cuts with a knife.
|
|
|
|
Post by notoes on Sept 21, 2021 6:31:26 GMT -5
Yup, you got one of the "rocket fuel catalyst" batch. I got two 5lb tubs of it, the first was worse than the second but I was able to use the second one up once I got the timing down - try mixing small batches (33-66 grams)quickly for just 30-60 seconds and you should be able to get it in the mold before it hardens. And by doing the smaller batch, you can get the details in without brushing on the HS-3. The up side of that batch is that you can demold very soon.
|
|
|
|
Post by DaleT on Dec 19, 2021 14:21:18 GMT -5
Ran into the same issue, amongst others, but with this issue discussed here, I just cut the catalyst amount in half and it worked fine. The batches(lots?) had changed from pink when mixed, to all just white, even when mixed. Then I saw a message somewhere about another user noticing that and I figured that was just the new normal. I had one 5 gallon batch of that go bad. It got too thick, and I just wrote it off to me mishandling or getting a old lot, or something. Then I ran into the super quick curing, discussed here. Wasted a few small batches finding that out and then my newest order, just now tried at the "new normal" catalyst amount and it looks like we are back to the old normal again. Didnt cure and now am back to 10 to 1 original ratio and trying again. Just poured 450minutes ago. And now its pink again. lol Very confusing especially when you have always mixed lots before (catalyst from one lot used in another lot has never presented a problem for me before)
|
|
|
|
Post by DaleT on Dec 19, 2021 14:26:32 GMT -5
Just poured 450minutes ago. 45 minutes.  |
|
|
|
Post by DaleT on Dec 19, 2021 14:38:29 GMT -5
1 more note. I've used HS3 a lot for many years. I prefer the pink, as it's a visual assurance of having the correct mix. Too far off one way or another and the shade of pink changes. I've caught myself more then once with an incorrect mix, before the pour. |
|
|
|
Post by notoes on Dec 25, 2021 9:19:22 GMT -5
Yes I've had that same problem and have been in contact with Alumilite on it. Some of the problem was the supply chain issue hit them too with some of their ingredients/containers and the tint is actually added by a human so when they have an overload of orders that they're trying to get out in a timely manner, sometimes human error comes into play. They're trying to get the tint into a more machine based adding but machines aren't perfect either so there are some tint issues. They're working on it and trying to get everything back to normal as quickly as possible. I like the pink too, it's a great help on the mixing part and put up with the white until the tint started to get back in the latest batches.
|
|
|
|
Post by DaleT on Dec 30, 2021 10:10:22 GMT -5
Maybe they could just supply the tint. Customer can choose if they want it. Other issues with that idea, I'm sure, but just an idea.
|
|
