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I have a rather nice old hand-built 531 frame and fork that I'd like to have repainted. Some companies offer bead-blasting to prepare it, but others offer chemical stripping.

Is this as good as bead-blasting for steel; does it offer any advantages?

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    Bead blasting is a general term. Blasting with crushed walnut shells is one type which should be pretty gentle to the underlying metal. Glass beads could potentially be abrasive to the steel and maybe even work harden the surface. – Eric S Jun 9 '19 at 16:23
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Both processes serve to remove paint coat from your frame. The only difference is that bead blasting may (or may not, depending on the medium used) scratch/damage the metal surface of your frame.

If you don't like that possibility, then you can opt for chemical stripping (especially if they'll treat the frame after for effective coat adhesion), but I'd consult with the establishment first on how your steel frame would react to the chemicals.

With that said, the link you gave also advertised giving treatment to your frame to prevent under-coat corrosion, so that's a nice touch for me.

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Abrasive blasting could use a variety of different materials, from harsh glass beads or powders through sand/silicates, to something quite gentle like walnut shells or sawdust.

The effectiveness comes down to the operator's skill and understanding of the surface and existing paint job.

If your bike was given a lot of coats of paint (primer, undercoats, top coats, and clearcoats) then there may be a dozen layers of paint. If it was a budget paint job there may be one layer.

One advantage to blasting is that it will leave the raw surface with microscopic indents which will help your primer coat or undercoat to key into the surface, improving adhesion of the initial coating.

I doubt that chemical cleaning will leave as good a surface. However Chemical soaks will get into corners better than large particle abrasive blasting. Small particle blasting will do corners just fine.

Overall cost is probably the deciding factor, and do remember that a frame stripped of paint is already rusting. You need to get a first layer on as soon as possible. Most blasting companies will flash it over with zinc spraypaint as part of the job, though check this.

Remember the frame needs prepping too - meaning bosses and threads need consideration. You have to remove everything including headset races and anything chrome.

Its reasonable to chase all the threads afterward too, but a pair of BB taps is expensive, so consider getting a LBS to do all this.

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Chemical stripping is preferred as bead blasting will effect the surface tension of the frame tubes altering the ride quality.

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  • Surface tension is a phenomenon associated with liquids. Could you add more detail to explain how this applies to solid bicycle frames and how it would affect ride quality? – David Richerby Jun 16 '19 at 21:47
  • All cold drawn steel has surface tension, The molecular structure of the steel at the surface has a certain hardness. Abrasives heat the steel as they remove the paint changing the molecular structure of the surface of the steel causing it to lose resilience. No high end bike builder ever "bead blasts" there frame sets prior to painting. It would certainly make paint adhesion better. Reynolds, Columbus, Vitus and True Temper do not recommend "bead blasting" as a preferred method of frame preparation. You want to ruin the ride quality of a high end steel frame, bead blast it. – Mike the Bike Jun 17 '19 at 3:43
  • Thanks. Please use the edit link to add that to your answer. (Comments are temporary and not indexed by search engines.) – David Richerby Jun 17 '19 at 9:15
  • I am beginning to understand that posting on your forum is a waste of my time and my over a half century of experience riding, building, restoring and maintaining bicycles. Good bye. – Mike the Bike Jun 17 '19 at 12:29
  • I'm sorry you feel that way. Honestly, though, your one-line answers give no hint of your expertise. If you put some actual detail into them, I'm sure they'd be well-received. As it is, you just assert something, don't explain why it's relevant and don't give any hint about why people should believe you rather than any other anonymous person on the internet. – David Richerby Jun 17 '19 at 12:49

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