All that matters, in my opinion, is that the seeds keep moist and cold. I think you can use anything that keeps the moisture. I use paper towels because it does the job. Also, the paper towels unfold easily so I can check if the seeds sprouted, without hurting the offshoot. I think you can plant them after you see that they sprouted. Every tree is different. Maybe your japanese maple seeds need different treatment than my apple seeds and acorns. Look on the internet for specific information about japanese maple seeds. I'm sure you will find enough. Again, I am not a proffessional, I just told you what and how I did that.