# Having trouble with HDPE finishes



## SharpshooterJD (Oct 9, 2012)

Hey guys just a quick question i'm currently in the middle of making a baby dragon out of black HDPE from simpleshot and the cutting worked fine with my jig saw and I got it rough shaped to my hand but I can not seem to get it smooth or even close to scratch free. So guys I need your help. What's the best way to final sand and finish an HDPE slingshot?


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## treefork (Feb 1, 2010)

Flame Polishing. A propane torch low flame gently applied to the surface in a brushing motion. Practice on a piece of scrap to get the feel. Amazing results.


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## SharpshooterJD (Oct 9, 2012)

Awesome thanks and does it have to be smooth before hand?


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## treefork (Feb 1, 2010)

sharpshooterJD said:


> Awesome thanks and does it have to be smooth before hand?


You will get much better results if you start out with a smoother piece. Play around with some scrap to build your confidence.


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## sharp eye (Jun 3, 2014)

Same technique to polish acrilic lucite edges.


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## SharpshooterJD (Oct 9, 2012)

Here is what i'm working with. I will dig out the dremel and try to get it smoother before I put it to the flame.


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## treefork (Feb 1, 2010)

Round those edges a bit with the dremel drum sander. Start at a 45 degree angle, then at the two new edges formed. Then smooth it all into a round edge. It will feel great in the hand for extended shooting sessions.


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## SharpshooterJD (Oct 9, 2012)

Here it is after the dremel it feels incredible but its ugly as heck and it won't get any smoother.


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## SharpshooterJD (Oct 9, 2012)

I have a small lighter and an alcohol wick burner for the flame but nothing else.


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## Rulz1523 (Aug 6, 2014)

Take almost any piece of stiff piping and wrap the sand paper around it and use it like a rasp or file. repeat for higher grits. Then I like to use tongs and carefully roast them over a stove top.... BUT BE VERY CAREFUL. If done wrong it can weaken the slingshot and release toxic gasses in the air, but if done right it leave the hdpe smooth.


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## SharpshooterJD (Oct 9, 2012)

Interesting idea maybe I just haven't tried hard enough with the sandpaper.


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## Rulz1523 (Aug 6, 2014)

I've realized that sanding it is much harder without the pipeing.


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## SharpshooterJD (Oct 9, 2012)

Yeah sanding can be a pain that might help Ill definitely try it thanks! So iv'e been sanding it and it's starting to look better I think Ill be able to get it smooth I just still don't understand the heating part I tried it with a lighter and it is hot enough to melt it but it doesn't really make it smoother.


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## Rulz1523 (Aug 6, 2014)

Heat it with a stove top and hold it with tongs so you dont burn yourself.


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## SharpshooterJD (Oct 9, 2012)

And the surface will become smooth?


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## Rulz1523 (Aug 6, 2014)

If and oly if the slingshot is sanded well enough.


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## Sharpshooter II (Apr 15, 2014)

yeah the best way would be to use a blowtorch as they get a really nice smooth finish !


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## SharpshooterJD (Oct 9, 2012)

Sadly all I have is a heat gun some cheap lighters and obviously a stove.


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## SharpshooterJD (Oct 9, 2012)

Anyone have pics of one in progress?


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## The Gopher (Aug 25, 2010)

I have found that i prefer to just keep sanding and sanding and sanding. Do not move on to the next grit until there are NO signs of scratches from the previous grit or tool. In other words, if you use a file for shaping, then go to 80 grit sandpaper and sand until all file marks are removed, then go to 120 grit and sand until all 80 grit marks are removed. keep going to at least 600 or 800, and you will be happy with it. it won't be a glassy finish but it will be very smooth. Black is about the worst for showing marks, and even if you flame finish it, it will show scratches and marks easily. here are a couple i made sanded to 600. the flash made them look a little frosted but these are smoooooth.


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## SharpshooterJD (Oct 9, 2012)

Awesome thanks Gopher! Yeah this is what i'm gonna do cause I really don't think the flame will work on black and yours look good I don't really care if they look amazing just presentable . I guess a trip to the hardware store is in order thanks again!


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## Susi (Mar 3, 2013)

This is a tried and true popular pattern you chose to make. Nice work.

We are just getting into HDPE, in fact tomorrow our first block melted down from all sorts of pieces of things. We experimented on sevaral final finish methods on scrap. If it's a cold day and you don't rub the sand paper too hard, PE gets harder the cooler it is, so it will finish more like a harder plastic, that is, you can get scratches out easier, if it's cold. Of course in the northern hemisphere it's hot. We wet sanded with wet paper dipping the test piece in ice water for a few seconds to cool it. Wet sanding produced better results all the way around than dry sanding and ice water even better. At night it gets into the forties nightly and even past freezing, 9000 ft. elevation of course on the Equator (Ecuador). Be super careful for you can singe the Hades out of your prize work. Past 800 grit go to 1000 if you can find it, (we can't find past 800 here in banana land) so use course automotive rubbing compound on a clean rag. Buffing is risky for if you use too much pressure on the buff wheel you'll melt the SS and that's ugly. Use light sporatic "quick gentle hundgges" on the wheel. it would help if you had a wet lapidary buffing wheel. (my hubby brought some of his cabachon equipment with him from the states 18 yrs ago). But use course automotive rubbing compound, clean it thoroughly two or three times with warm water and detergeant, then use fine automotive rubbing compound. I like an old Tshirt wrapped around a shoe brush for this hand buffing job.

If you want a window polish, that will take a lot of work and since PE scratches so easily, is it worth it or would a nice matt or semimatt finish be more practical? Less shine means the zombies and game won't see you as much. (theory here only).


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## Themexicanshooter (Mar 12, 2014)

Sanding works the best for me start with rough and then go smoother grit, you will get great results


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## SharpshooterJD (Oct 9, 2012)

Thanks for the help guys I should have a video up soon of me making it.


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