Wednesday, July 17, 2013

Vat Coating #1: Sylgard 184

So, new vat is constructed. Nice and water tight! Life is easy when you have access to all the tools you need isn't it?

Now that the vat is constructed, onto the coating. This coating is whats going to help prevent your cured resin to adhering with the bottom surface of the vat, we don't want that because we want to 1) be able to lift the platform to do the next layer 2) lift/tilt to allow resin to flow back into the just cured area. I have purchased Sylgard 184 and PTFE film (adhesive backed and non-adhesive backed), check the hardware section for links) for this task. 

First up is Sylgard 184. This seems to be where most folks with bottom-up resin printers start with. It's what the B9 uses and can be found on the various DLP printers you can see on Youtube. In general, this stuff is used for solar panel's silicone that is non-UV retardant and cures clear (pretty much optically clear). Makes sense for what it's used for. Make sure if you do buy some Sylgard 184 that you get the legitimate stuff that is Dow Corning brand, there are knock-offs of.

I will say that a lot of the folks I talk to advise on not using it, but me being the stubborn person that I am, will give it a try anyways.

Sylgard 184 is a two part solution that needs to be mixed with the ration 10:1. The vat I currently have has an interior area of 5" by 6" (pretty much an 1" offset of the build platform I have, which is 3" by 4"). Doing some basic calculations, I arrived that I would need approximately 45-50 mL to get a decent coverage. Whipped out a small beaker and got to mixing.

During the process, the two part mix will get really smoky and full of bubbles. You might think this is a bad thing, but rest assured, all those bubbles do indeed disappear. Mix for 3 or so minutes, you really want to make sure that things are mixed really well for best results (and of course make sure you measure accurately for the 10:1 ratio).

Find a nice and leveled surface for your vat (a leveled surface is key in getting an even bottom for your print surface), pour in the Sylgard 184 and spread it evenly. Gravity will take care of the rest and things will settle. Now leave it there for 24 hours (probably more time then needed, but it can't hurt to leave it a bit longer!). On that note, you can cure the Sylgard faster by placing it in an oven up to 80C (careful, acrylic may warp, this might be a good reason in the future to use glass). If interested in that route, be sure to read the info on the Sylgard 184. 

Few minutes after...
about 30-45 minutes after...SO CLEAR! I did use a need to poke a few air bubbles.
Resin should be in tomorrow (I guess that's now today at the time of this writing) and I should have the vat and baseboard should be constructed then too. Should be "printing" tomorrow...printing well or not is a whole other story. Exciting nonetheless!

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