It was only a couple of weeks ago I was asking the same thing how do you make it safe as "possible" to inject 16mg ER Hydromorphone and not thick goo. This is what I do please don't try this method unless you are going to do it anyway possible.
Step 1: First up you must learn as much as possible on injecting. ( Hygiene, Draw back etc.) Use hand sanitiser thru out process.
Step 2: You need a 5ml syringe 32 ga needle, 5 X 1ml syringes ga?, 8 filters these filters are just basic cigarette shape, as many alcohol wipes as possible and a disposal container. (I buy two sharps kits and a 5ml syringe I end up with easily enough)
Step 3: Clean the coating off pill with alcohol wipe. The pill will come up white and grey, separate the white from grey using a hot clean knife and board leaving as little grey as possible. Throw out the grey side of pill.
Step 4: With the thin white pill you have left cut in half vertically. On the pill you see a layer of film remove this with fingernails or tweezers. ( if using fingernails which is easier make sure you wipe pill with alcohol wipe after fuck knows whats under your nails) Place in small clean container.
Step 5:I have bottle water frozen into 5.5 ml ice cubes which I chip into small bits which I place in the container with the white parts of the pill which I mix with a spare clean syringe. Mix with the melting ice cube until it becomes gooey. Keep doing this until it turns into a liquid with the water, leave for 5 minutes at room temperature and mix again.
Step 6: Place two filters into the 5ml syringe by taking the plunger out. Push filters down inside with the 1ml syringe you did the mixing with. Put plunger back in. Draw up contents of the containers with the 5ml syringe thru filters until fill. Remembering to use alcohol wipes when necessary.
Step 7: The container will have a drop or two that wasn't drawn up eat it or suck a filter you don't want that. Inject 5ml syringe into container, now with this filtered mix put a filter on the needle of of one of the 1ml syringes and draw it up, repeat this with other syringes and you should end up with four and half 1ml syringes with pretty clear solution.
Step 8: Make you own choice what you are going to do with it! It should be more of a liquid that goo, but this doesn't make it 100% safe remember. This 1ml hits should give you a mean hit heaps better than all 16mg of goo into 1ml. Some reason I get away bigger hit than the times I did goo and that's meant to be four times stronger.
I'm smashed for last night so I hope it makes a little sense to anyone reading this. I really didn't put any time into grammar.
By no means I have proof this is a lot safer I'm just putting up what Ive been doing in the last two weeks.
BE SAFE