<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>BillieRuben</author><text>- PLA as a material is at least food safe (though food safe and body safe aren&amp;#x27;t the same). But! The material passes through nozzles which probably have lead in them etc. even if that&amp;#x27;s of negligible consequence though the main issue with making something body safe is the layer lines, which retain moisture and breed bacteria.&lt;p&gt;- yes, concave surfaces are dang near impossible to smooth.&lt;p&gt;- plenty of household release agents don&amp;#x27;t work in a silicone to silicone mould, or impede the cure of platinum cure silicone (the body safe kind), and if you bugger it up you&amp;#x27;re just wasted the mould and the dildo&amp;#x27;s worth of silicone which is $$$.&lt;p&gt;- I just used PLA. the beeswax doesn&amp;#x27;t touch it for long, you literally pour it in and immediately back out. Because the print is hollow on the inside and because beeswax has such a low specific heat capacity it cools instantly, and this all works, my pics are proof.&lt;p&gt;- silicone doesn&amp;#x27;t bond to PLA, no, but you need to smooth the layer lines, which brings us back to point 1....</text><parent_chain><item><author>dTal</author><text>The core of this technique is the use of beeswax to act as both a filler&amp;#x2F;smoothing agent and mould release. A clever hack - but I&amp;#x27;m confused by some things:&lt;p&gt;- the assertion that 3d printed materials are not body safe; PLA (the most common 3d printing material) is nontoxic and used for utensils (although agreed that the layer lines are a hygiene hazard)&lt;p&gt;- the description of the &amp;quot;traditional&amp;quot; method as printing a positive shape, then casting a negative in silicone, and then casting a positive &lt;i&gt;also&lt;/i&gt; in silicone (with release agent, presumably because silicone bonds to itself). Why would you not just print a negative directly - as indeed she later does? Is it because she considers the concave surface difficult to sand smooth?&lt;p&gt;- Why is release agent &amp;quot;$$$&amp;quot;? There are a variety of extremely cheap household items that work as release agent, notably dish soap.&lt;p&gt;- Pouring 100C beeswax into a print. This is &lt;i&gt;well&lt;/i&gt; above the glass point of PLA. She doesn&amp;#x27;t say what material she&amp;#x27;s printing with, which may explain the earlier remark about not being body safe.&lt;p&gt;- The need for any sort of release agent. Silicone does not bond to thermoplastic, at all. She&amp;#x27;s not casting silicone in silicone, so what&amp;#x27;s the problem?</text></item></parent_chain></comment><story><title>3D Printing Sex Toys</title><url>https://www.billieruben.info/post/3d-printing-sex-toys-a-quick-easy-and-safe-method</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>h2odragon</author><text>I wouldn&amp;#x27;t fear a PLA thing first use; but cleaning it thoroughly enough to re-use is going to be a challenge without special effort applied to finishing it after printing.&lt;p&gt;Beeswax temp: Thermal mass of the print is probably high enough that it sucks the heat out of the wax before melting much surface feature. in this case, smoothing bumps is beneficial.</text><parent_chain><item><author>dTal</author><text>The core of this technique is the use of beeswax to act as both a filler&amp;#x2F;smoothing agent and mould release. A clever hack - but I&amp;#x27;m confused by some things:&lt;p&gt;- the assertion that 3d printed materials are not body safe; PLA (the most common 3d printing material) is nontoxic and used for utensils (although agreed that the layer lines are a hygiene hazard)&lt;p&gt;- the description of the &amp;quot;traditional&amp;quot; method as printing a positive shape, then casting a negative in silicone, and then casting a positive &lt;i&gt;also&lt;/i&gt; in silicone (with release agent, presumably because silicone bonds to itself). Why would you not just print a negative directly - as indeed she later does? Is it because she considers the concave surface difficult to sand smooth?&lt;p&gt;- Why is release agent &amp;quot;$$$&amp;quot;? There are a variety of extremely cheap household items that work as release agent, notably dish soap.&lt;p&gt;- Pouring 100C beeswax into a print. This is &lt;i&gt;well&lt;/i&gt; above the glass point of PLA. She doesn&amp;#x27;t say what material she&amp;#x27;s printing with, which may explain the earlier remark about not being body safe.&lt;p&gt;- The need for any sort of release agent. Silicone does not bond to thermoplastic, at all. She&amp;#x27;s not casting silicone in silicone, so what&amp;#x27;s the problem?</text></item></parent_chain></comment><story><title>3D Printing Sex Toys</title><url>https://www.billieruben.info/post/3d-printing-sex-toys-a-quick-easy-and-safe-method</url></story>