I suppose most people have heard that the silica gel with cobalt (blue color) is less safe than the orange kind, but did you know that there are two different orange indicator dyes? One turns from orange to dark green, and the other turns from orange to bright green. The first uses Methyl Violet as the indicator dye, and the second uses Chlorophenol Red. Of the two, Chlorophenol Red is thought to be less toxic.
There are yet other dyes out there, but this is as far as I’ve gotten. Maybe some of you know more. There seems to be no difference at all in price of the silica gel desiccant regardless of which indicator is chosen, so for now I’m opting for the Chlorophenol Red.
Perhaps there are other considerations also. For those of you who do buy silica gel beads that contain a moisture indicator, which dye is it that you prefer, and why?
Same bead size? I’ve noticed two ranges commonly advertised: 2mm-4mm and 3mm-5mm. Since this stuff is sold by the pound, the cost is the same either way. So, which is the better pick? I’m guessing the smaller size range might outperform, maybe depending on how it’s arrayed, because of greater surface area.
Consider the midpoints of each range: 3mm vs. 4mm. The 3mm beads would have 33% more surface area than the 4mm beads for the same overall mass.
So, not a huge difference, but maybe enough that you might notice if you were comparing head-to-head.
There are also silica gel beads which turns from orange to clear. Those utilize Phenolphthalein as the indicator dye. Again, Chlorophenol Red is regarded as safer than Phenolphthalein.
I’m not aware of any other indicator dyes or color transformations commonly used, but maybe there are. If you know of others worth considering, please post.
I realize safety isn’t a popular topic. I get that. This is for those of us who want to compare notes so as to (hopefully) choose as wisely as we can given current information.
From what I’ve read, Chlorophenol Red is of such low toxicity that I’m not worried about it, especially in relation to everything else in the environment. I had considered no indicator dye at all, but so far I’m finding that having an indicator is useful for what I’m doing.
For anyone interested, the one I picked was this:
which, if I’m not mistaken, does use Chlorophenol Red as the indicator and also has the smaller size range beads (2mm-4mm). That compares with the dry-and-dry brand, which uses methyl violet and has the larger (3mm-5mm) size range beads. Prices are the same either way.
I personally went with the cheapest orange silica desiccant beads on Amazon that are 3-5mm. I knew they were supposed to be less toxic and color didn’t matter to me, so I figured that’s the route I’d go. Didn’t realize there was even differences in the orange versions, but I’m not sure it really matters to me. I use a toaster oven to dry them that’s used for everything but food, so I’m not really concerned with the toxicity.
I find that I never look at my beads to see if they’ve changed colors, I just watch my hygrometers to see when I need to change them out. The only real benefit to having the colored version is that you can tell when they’re dry after sticking them in an oven.
I did the same thing as well until it occurred to me that when I weighed my filament before putting it into the dryer, why not way the 50g silica packets I had too. I then simply place the silica in with the spool to be dried and weighed it afterward too. Turns out that the principle for measuring moisture using weights works the same for silica.
Here’s another method I tried. I was initially skeptical about the claim that silica gel can absorb up to 25-350% of its weight in water. To test this, I conducted a simple experiment using the weighing method.
First, I measured and weighed a specific amount of water and weighed some fresh, desiccated silica gel beads straight from the bag. I then sealed the beads and the water in a plastic container, placing a hygrometer inside to monitor the humidity. I stored the container in a warm location to encourage water evaporation. Once the container reached equilibrium and the beads changed color (indicating moisture absorption), I weighed the beads again and measured and weighed how much water remained.
The results showed that the beads had indeed absorbed close to 30% of their weight in water, coming close to confirming the manufacturer’s claims. This method was a straightforward way to validate the silica gel’s absorption capacity as well as providing a more accurate method other than color to gauge when the packets needed recharging.
The packaging didn’t specify, so I compared a sample of each. They look the same size to me. I would guess they are the 2mm-4mm (I didn’t pull out my calipers to confirm, but they didn’t look large enough to reach 5mm). But I have been super happy with them.
You bring up a really good point that I hadn’t considered; you can weigh your beads to verify that they are dry. I was just drying some of mine today and took them out when the time was up and the beads had turned back to their original color. Thinking they were good to go, I stuck them into a plastic Tupperware container to cool down and stay out of the open air. After closing the lid, I noticed that it had immediately fogged up with steam coming off of the beads, which meant they weren’t fully dry yet. I had to stick them back in the oven for a second round to get them fully dry.
Now I really want to try out your test on my beads I’m using to see how well they absorb water. Would be a great way to determine if I’m getting the best results or not. Will have to compare the two brands I have and see which one takes the win. I’m betting the beads I purchased from Hobby Lobby are going to lose out on my Amazon purchased beads since they don’t seem to perform as long.
One thing you can try, and let’s compare notes afterward. I’ve noticed that after a reasonable amount of drying in a filament dryer, say overnight, I don’t get a 100% return to the filament’s original factory weight out of the bag. I’m unsure whether this is due to my drying methods or if the filament reaches a saturation point.
For example, if I had a 50g bag of filament, I’ve found that it never returns to exactly 50g but instead stabilizes around 53g. Oddly enough, I can always get it back to 53g, but never to its original factory weight. One thing I haven’t tried yet is grinding the silica gel beads into smaller pieces to see if the increased surface area to volume ratio has any effect.
Went ahead and did a test with 35g of orange indicating silica beads fresh out of a container, never used. Put them inside a container with water that i occasionally set on my a1 mini bed to heat up to 55c to let some of the water evaporate and create a high humidity environment. I left them in there for about 20 hours and weighed the beads. They weighed in at 41.5 grams, which is 18.6% absorption. Not as a good of a result as what you experienced, though I might get better results if I leave them in there longer. Dried the beads spread out on a pan in my toaster oven at 225F for about 45 minutes. They went back to their original weight of 35 grams, so I did not see the same results as you are seeing here either.
Some things to consider. The absorption rate of only 18.6% might be due to the beads needing longer time to fully absorb the moisture. I found that I needed to stir the beads occasionally to bring the dry beads to the top, so if I continued for another day, they may produce better results. Since drying the beads brought them back down to their original weight, it may be due to a couple of factors. I might not have let them reach their full saturation point and so they wouldn’t hold on to any extra moisture. The beads may have already absorbed some moisture in the factory container since it’s already opened and so the original weight might have been already skewed.
Thanks for sharing those results. This is very helpful data. If I remember correctly, my absorption test ran over five days. I was out of town and left the experiment in a sealed plastic tote. Now, regarding when they reached saturation, was it three days or five days? I can’t say since I didn’t measure in between. However, it would be interesting for someone to collect that data at some point to verify what the absorption curve looks like.
For example, if we keep the desiccant within, say, 10% of its pre-absorption rate, does it matter? But if we know that absorption at, say, has reached 20% max weight is poor, an argument could be made to never let the color change too much, just to ensure the desiccant is at full capacity—or even consider doubling or tripling the amount of desiccant.
I thought about this when I realized the largest water loss I ever saw was a brand new 1kg filament with a cardboard spool, and that was 12g. So, if I have a 50g bag with a 30% max absorption (15g), I might want two 50g bags to ensure the desiccant never comes close to its max absorption. With a dryer that can spool live filament, this hasn’t been a concern so far.
Also, this is why I use absorption cards in my storage bags. Unlike hygrometers that only report current conditions, the cards show absorption over time, giving me a clearer picture of what the filament may have absorbed.
Why in God’s name are you guys still relying on imperial measurements instead of metric, I really can’t comprehend… gallons, lbs…miles, inch, foot, feet, Fahrenheit … instead of kg for weight, liters for volume, and meters for dimensions, Celsius for temperature…keep it simple people, life’s already complicated, don’t over-complicate it even more…
I was not aware of that yet.
