[Jewelry making - Article 01110] - Re: [Orchid] Masking for sandblast

[MJOAT]

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    In Media blasting, the first questions you have to ask yourself is. 

        What is the type and hardness of the media I'm going to use? 

        What is the size of the nozzle at the discharge? 

        What is the distance I can keep the nozzle away, from the item
        being blasted? 

        What is the size of the grit I'm using, whether it is walnut
        shell, glass bead, garnet, steel shot, plastic or sand? 

        What is the effect that I'm going for surface finish, texture,
        deep etch,removal of paint,curd or other surface contaminant, or
        prep of the surface for another type of coating. 

    As of the above will determine you choice of mask or friskit
    material. If you are using a small abrasive blasting unit either home
    made or bought. The kind glass artists use a: 

    The Paasche AEC Eraser set works like a miniature sandblasting tool!
    The long lasting carboloy tip removes old paint, rust, or corrosion
    without damaging the undersurface. It's powerful enough to carve
    designs in wood or to etch on glass and can also be used for
    cleaning fine instruments. 3045 PSI is required. 

    Dick Blick's or most hobby shops art supplies stores have them. 

    Or a small cabinet type with a smaller nozzle. You can use a lighter
    masking agent. 

    Any tape, from cellophane, packing, duct or the stainless steel
    muffler tape will work. Any paper or card board will also work, For a
    mask held in the hand or taped in place for larger areas. Cling wrap,
    plastic wrap painting plastic mask can also be used. You can use the
    afore mentioned tapes or make up your own with a spray adhesive to
    just about anything. 

    Contact vinyl shelf paper/plastic makes a great low cost mask with
    easy removal. Old bumper stickers or the lazer/inkjet printing
    sheets work. 

    The best way is to make up a test board with a number of samples and
    try blasting it at assorted pressures and distances. 

    As to liquid applied masks the only thing you have to remember is.
    It has to be removed from what ever you apply it to. if the surface
    is rough or lots of highs and lows. It can be a real pain if there
    isn't a solvent that will remove it it can ruin a piece. But nail
    polish, dip it rubber coating, rubber cement, thinned caulking,
    latex rubber and heavy layer of acrylic paint can be used. 

    The rubber mask that has been mentioned for blasting is
    about.025.030 and up. A monument maker would use a thicker mask for
    heavy carving. You could use rubber lab aprons with spray glue. A
    lot of the monument people will sell a small section if you might
    call and ask them, before popping in asking for some. 

    Electrical will work and you can get it in wide widths at supply
    houses. But be aware some brands leave a sticky mess that needs to
    be removed. 

    For texturing or patterns on the surface. Something else for your
    consideration is blasting thru metal or fiberglass or plastic mesh
    or screens. laundry bags and the vegetable bags. Along with the
    plastic protection wraps that some drill bits and mill cutters come
    in. 

    The idea of cutting on plastic is nice, but the use of plate glass
    with the tape on it and cut with an #11 xacto blade is the sign
    industry standard when doing free hand work. Always use a fresh
    blade each session. Another tip is to use a burnisher like a bone
    folder, plastic pen top or wooden polished clay or wax tool along the
    edge of the mask if it is sheet goods. As if any media can get under
    the mask it generally will all follow and peel up. 

    Keeping the nozzle at 90' to the surface that you are blasting works
    to insure a crisp edge to. 

    Also if you are using masking tape to lay down a liquid mask, make
    sure you try it out on a test panel before the piece. as some
    liquids will peel up with the tape if they aren't cut with an exacto
    first. 

    Remember, always do a test before starting in on the item you are
    doing. As it really does save a lot of do overs! Ben there, redone
    that, to many times. 

    And the last item, as it has been discussed on this site before. But
    do to the new people and the people that don't do searches on the
    site. When you SAND blast using SAND/SILICA etc. 

    You can develop silicosis: 

    Silicosis is a progressive disease that belongs to a group of lung
    disorders called pneumoconioses. Silicosis is marked by the
    formation of lumps (nodules) and fibrous scar tissue in the lungs.
    It is the oldest known occupational lung disease, and is caused by
    exposure to inhaled particles of silica, mostly from quartz in
    rocks, sand, and similar substances. 

    You can read more here
    http://www.answers.com/silicosis?cat=health&gwp=13 Or at your
    favorites search engine.
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