Blasting media......

  1. slim_boy_fat

    slim_boy_fat Forum Supporter

    I have a very small area of surface [no penetration] rust [approx 3" x 3/8" ] on the bottom of my boot lid and plan to sand blast it before treating, priming and painting, using the small Lidl blast gun the small one with a bag for feeding the media and various shaped nozzles [spot, edge,round etc] which looks very similar to this Google image

    [​IMG]

    I've no idea what size of nozzle it has and googling their site fails to find it - it's been lying in a cupboard for years :ashamed:. I'll be using it with my small Lidl compressor :whistle:

    I've been googling all sorts of media to see what might be best for such a job but am now confused, the choice is bewildering and I'd like the Collectives's recommendations before proceeding. Quantity will feature as well as some stuff is only available as packs of many kilos and given the size of job it'd be a waste to commit to too much.

    So, kiln dried sand, alu oxide, crushed glass, crushed walnut etc - and what grade'd be best? :dontknow:

    Over to you, lads :hug:
     
  2. mrfuzzy

    mrfuzzy Forum Supporter

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    polystrip disc / cup brush not be more economical / almost as effective?
     
  3. slim_boy_fat

    slim_boy_fat Forum Supporter

    Hadn't even considered those............:ashamed:

    Thinking about it, if a suitable blasting set-up was settled on, I dare say I'd find other uses for it - awkward shapes, corners etc?
     
  4. Mee Banned

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    Here and There
    Crushed glass or aluminium oxide for me, but keep the pressure down to prevent distortion of the panel and bring it up steadily and use your judgement.
     
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  5. rcx132

    rcx132 Philip

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    The Lidl gun comes with media that looks just like JBlast Superfine or Sealey grit. The Sealey stuff is £25 a bag. JBlast is way cheaper if you can find a local supplier.

    On Google there's lots of images show how aggressive each media is. An image of a rusty leaf spring that's been masked off and blasted in sections with different media.

    After that it's a case of deciding if you want expendable or reusable and cost.
     
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  6. Burdekin

    Burdekin Chief Bodger

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    I'd have a trial with kiln dry sand first and see how you go before. A P3 dust mask would be a good idea as well. Let us know how you get on, be interested in how the sandblaster goes.
     
  7. 8ob

    8ob Member

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    Another vote for the kiln dried sand, by far the cheapest and attainable for experimental purposes.

    Bob
     
  8. 8ob

    8ob Member

    Messages:
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    moscow on thames
    I have got blasting equipment here but when I need lots of gear done I get a mate in with his big setup, interestingly he would use a fraction of the sand I do and blast ten time the gear. He explained that with a massive air volume you only need to introduce a small amount of grit to achieve the results, with my kit and smallish compressor the sand needs to be in large quantities to make progress.

    Bob
     
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  9. slim_boy_fat

    slim_boy_fat Forum Supporter

    Wickes grade [grit size] be OK for the job, but I've tracked an identical gun down at Machine Mart here https://www.machinemart.co.uk/p/sb5-spotblast-gun/ and they recommend using aluminium oxide available in 7.5kg tubs https://www.machinemart.co.uk/p/7-5kg-60-80-grit-aluminium-oxide-powder-2/ at what looks to a complete novice to be a reasonable cost, which I can get sent to my local Post Office for collection at no delivery surcharge :thumbup:

    Any reason not to go for this, seems good value given that I may waste some practising on scrap first to get the feel for the job? See edit....

    EDIT: Mhhhh, this http://www.ebay.co.uk/itm/1-x-25kg-...nd-/162009651063?_trksid=p2385738.m2548.l4275 is a distinct possibility given what the lads have said - and free delivery too! I think I have seen the future, thanks for all the contributions as ever :thumbup:
     
  10. rcx132

    rcx132 Philip

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    Location:
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    Machine Mart alu oxide price is ok actually (for a change). I just bought a 25kg bag from a trade supplier and it cost £30 (£1.20/kg). Compare to Machine Mart £1.60/kg, not bad. I don't see why they recommend alu oxide, the gun does loose media, so cheaper expendable grit would be fine because even though it is classed as expendable it can be reused many times. I had the stuff going through my blast cabinet for months before I knew it was not supposed to be reused.
     
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  11. 123hotchef Member

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    Kent
    presumably with Kiln dried you dont need a cabinet as it is good for the lawn!
     
  12. rcx132

    rcx132 Philip

    Messages:
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    Other times Machine Mart prices are not that great :p ...
    Same Chinese compressor, 60% dearer...

    [​IMG]upload img
     
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  13. 123hotchef Member

    Messages:
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    only good when you have a vat free day
     
  14. rcx132

    rcx132 Philip

    Messages:
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    London, UK
    We really should get some sticky about choosing blast media, it's really confusing and people keep asking. I find these sorts of pictures really useful in choosing:

    [​IMG]
     
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  15. rtbcomp

    rtbcomp Moderator Staff Member

    Messages:
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    Location:
    Sheffield UK
    Don't use building sand or grit sand, there are too many big bits in it and it's damp. I've had damp "Kiln dried" sand from Wickes and B&Q. B&Q recycled glass for paving is also useless for blasting for the same reasons.

    Pity that diagram doesn't show J-Blast and glass grit.
     
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  16. slim_boy_fat

    slim_boy_fat Forum Supporter

    Ahh, I've just this minute bitten the bullet and ordered the sand I linked to in post #9 as supply was down to 5 bags available. :doh:

    However I'll be using it in such small quantities for the job(s) I have in mind so it won't be too much hassle to sieve and dry it...and Summer's coming. ;) If it proves to be a disaster I'll not have wasted too much of my money [remember the free delivery is a significant factor up here] as I can try an alternative and use the sand to top-dress the grass. :cool:
     
  17. 8ob

    8ob Member

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    The guy that does our blasting only uses kiln dried sand, he does car body shells up to artic trailers and forestry kit with the same gear. He turns the whole show down when doing body shells to avoid panel distortion, its a bit more involved than most people think but we are only talking about a bit of rust on a panel here. Glass blasting was causing catastrophic failures on mechanical components for the REME`s reconditioning plant, the glass dust could not be flushed out of the castings and was hanging up in the pores which after a while got into the lubrication systems. They went over to coconut shells which solved the problem.

    Bob
     
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  18. WorkshopChris Forum Supporter

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    I am supplies he runs the risk of using sand as there are some serious HS consequences, silicosis related.
     
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  19. Mr shiney Member

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    1,218
    UK northants
    Sand is extremely bad for you.... As chris above states, silicosis is a major risk.
     
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  20. 8ob

    8ob Member

    Messages:
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    Location:
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    mrfuzzy and WorkshopChris like this.
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