Question How to increase the hardness of methamphetamine after crystallization

[chef learner]

Please help me improve some of my knowledge, because currently I can't find any relevant solutions.

After I kept trying to recrystallize D-methamphetamine, every time it turned into white transparent crystals (almost completely transparent, like glass), I asked a local manufacturer to check my sample and told me that the taste of the product met the requirements, but the crystals needed to be re-crystallized. It is harder. What parts of the synthesis should I pay attention to, or what methods can be used to increase the crystal hardness?

Additional inquiries:
I crystallize D-methamphetamine. After each crystallization is completed, I take out the solid and keep the remaining liquid and put it in the refrigerator to crystallize again. These products are also D-methamphetamine, right, and they can continue to crystallize. Is it right until D-methyl oil completely becomes crystal?

Please advise, thank you for your help

 

[Osmosis Vanderwaal]

So you are making it from p2p? phenylacetone?PMK? p2NP? Then half of it should be D and half L. It is possible to racemerize L-meth to D,L-meth and extract the D from it again, but it's expensive or a long project. if you are using D-tartaric acid and non-polar solvent then yes the crystals should bre D. If the creystals are clear, that means they are high purity usually. The reason to recrystallize is to grow bigger crystals and the trick is to cool it down slowly and then leave it for a long time. Those huge crystals take a month to grow

 

[chef learner]

I made P2P through 5449+phosphoric acid, and used NaBH4 reduction to make methamphetamine, and then used L-tartaric acid to separate the free bases of L and D.

 

[chef learner]

If you are using L tartaric acid (87-69-4), the solid after mixing is L- and L-tartaric acid. Put the whole bowl in the refrigerator for one day, take it out, add a little methanol and stir, use a filter funnel to separate the solid from the methanol. D-methyl free base can be obtained by adding the liquid to sodium hydroxide solution.