It’s pretty standard for White Labs yeast in my experience. The contents end up carbonated from the yeast fermenting the wort they’re packaged in. Makes the “shake before opening” instructions on the vial about as friendly as they’d be printed on the side of a bottle of Coke.
I have good luck with cracking the seal to release the pressure, then shaking the yeast to get it back into suspension, then opening slowly to let the gas off again. You’ll still get a little juice, but it’s not nearly so bad.
I had the same experience when I first used white labs yeast. Now when I get ready to prepare a yeast starter I usually very carefully crack the seal just enough to start seeing bubbles float to the top of the vial as soon as I take it out of the fridge. As I let the yeast warm up to pitching temp I will go back shake it and slowly open it until the bubbles start going to the top again. Repeat this process a few times until you can safely remove the cap without any spillage. I think your starter should be fine but never hurts to step it up at least once if you can.
That’s a great yeast strain btw. I’m on generation 4 with mine, and it keeps chugging along. Great for IPAs because it accentuates hop flavor. Also have been getting 85% attenuation with it consistently.
I would be more concerned that the starter is not going to be done in 1 day rather than you don’t have enough yeast. Many a good/great beer has been made with 1 vial/smack pack per 5 gallons of beer.
And like most posts for help/advise, you have not given enough information for anyone to double check your math.
You are making a IPA, 10 gallons. What is the OG?
Your original post didn’t mention how big of a starter. You updated that later to be 2000ml. Which equals 67.6oz. There is a mention of mason jars being used, 2 of them. Are you using quart mason jars? That is 32oz. Most likely you don’t have them but ~3/4 full. Just guessing that you would only have 50-55oz of starter.
Or are you using a 1/2g mason jar. Again, you would only have ~55-60 oz in it.
I would not bother with spending another $8 for a 3 vial of yeast. Use what you have.
I have a 2000ml mason jar. It was filled to the brim with 2000ml of water, so I ended up using about 1750ml so the starter wort is slightly more concentrated, so it should even out I think.