Probably a stupid question regarding CA finish on acrylic

Discussion in 'Woodturning Discussion Forum' started by Bruce Schoenleber, Oct 22, 2017.

  1. Bruce Schoenleber

    Bruce Schoenleber

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    I doubt I will ever turn anything acrylic, yet I enjoy seeing what others do. It seems that CA is a very popular finish with those who turn acrylics. Why? It seems to me that acrylic is a hard plastic which can take a high polish. What does adding an extra layer of plastic finish yield. CA glue is not cheap and it seems most finish applications use somewhere upwards of 6-12 coats. Strikes this uninformed person as a lot of work and expense for what result?
    Not trying to step on any toes, just bewildered.
    -bruce
     
  2. Tim Leiter

    Tim Leiter

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    When I turn acrylics I sand with 240 grit then sand with 600 grit. I apply EEE Ultra Shine and then finish up with 2 coats of Shellawax. I like the looks and feel of the finished piece and so do my customers. (I don't do any finishes with CA due to health issues and I don't like the feel of the plastic finish). I go though the same sanding and finishing process with wood blanks. Sometimes the wood blanks need more coats because some of them absorb more of the finishes than others.
    I have read that a lot of people don't use any finish on acrylics but I prefer to finish them my way. Just do the turnings the way you want and that satisfies you.
    Good luck.
     
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  3. Bill Boehme

    Bill Boehme Administrator Staff Member

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    I put CA finish on wood, but for acrylic pen blanks I use Micromesh going up to 12,000 grit to get a glass shine. I wasn't even aware that anybody put a CA finish on acrylic and I agree that it seems to be unnecessary and maybe even making finishing more difficult than it needs to be.
     
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  4. Lamar Wright

    Lamar Wright

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    When I turned pens I used CA for finish on both wood and acrylics. Not so much for the shine but for the ware pens get from daily use. CA finishes are tough and can take a lot of abuse. However, the shiny look you get is a bonus.
     
  5. Bill Boehme

    Bill Boehme Administrator Staff Member

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    One of the best features of acrylic plastic is its high scratch resistance as well as optical clarity which is why it is the preferred material for prescription glasses. Polycarbonate plastic is used for safety glasses, but despite its toughness is far easier to scratch than acrylic.

    BTW, CA is an acrylic plastic.
     
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  6. Grant Wilkinson

    Grant Wilkinson

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    I'm surprised at Lamar's reply. I've never read of someone putting CA onto acrylics. For my acrylic pens, I sand to 600, then use Novus 2 and 1 to finish them off. I've never had any issues with the durability of the shine the I put on acrylic pens.
     
  7. Gary Beasley

    Gary Beasley

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    I usually polish my plastic parts as is, BUT if I encounter an air bubble or other defect CA does a good job filling and otherwise making that defect go away. Worthless wood castings or anything else with wood mixed in sometimes need CA to even out the shine. Glitter castings sometimes need a bit of CA if a bit of glitter pokes through the surface.
     
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  8. Bruce Schoenleber

    Bruce Schoenleber

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    Thanks Gary. That explains the acrylic on acrylic mystery to me quite well.
     
  9. Lamar Wright

    Lamar Wright

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    Hi Grant, that's odd, most of all the pen makers that are members of IAP in my area use CA on their acrylic pens also. This is just another step in the process that I learned years ago. It is not mandatory by no means with acrylic pens. It is a more critical step for wood pens because CA after application and polish protects the wood better than friction polish or wax just IMO . Happy turning.
     
  10. Raul McCai

    Raul McCai

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    Some excessive-over-information you may or not find interesting:
    http://na.henkel-adhesives.com/us/content_data/Hard_to_Bond_Plastics756739.pdf

    http://www.machinedesign.com/adhesives/guidelines-bonding-plastics

    http://www.craftechind.com/6-types-of-glue-for-plastic/

    http://na.henkel-adhesives.com/us/content_data/397189_LT2197_Plastic_Guide_v6_LR.pdf

    http://www.caglue.com/Frequently-As...-from-Satellite-City-Instant-Glues_ep_42.html
     
  11. Bill Boehme

    Bill Boehme Administrator Staff Member

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  12. John Torchick

    John Torchick

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    First, my father said the only stupid question was the one not asked.
    I don't use CA on synthetics. I turn acrylic/synthetic and then hit it with the series of Micro Mesh and then use Hut Ultra Gloss for the final step.
     

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