Soda blasting
From Crankshaft Coalition Wiki
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[[Image:65RollsRoyceSodaBlasted.jpg|350px|thumb|A 1965 Rolls Royce after being soda blasted.]] | [[Image:65RollsRoyceSodaBlasted.jpg|350px|thumb|A 1965 Rolls Royce after being soda blasted.]] | ||
Soda blasting is the use of sodium bicarbonate ("baking soda") or sodium bicarbonate-based materials as blast media for paint stripping. | Soda blasting is the use of sodium bicarbonate ("baking soda") or sodium bicarbonate-based materials as blast media for paint stripping. | ||
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==Soda blasting history== | ==Soda blasting history== | ||
| − | Soda blasting was originally used as a method of stripping/cleaning industrial machinery. It was developed in the 1980's, and was most notably used | + | Soda blasting was originally used as a method of stripping/cleaning industrial machinery. It was developed in the 1980's, and was most notably used in the restoration of the Statue of Liberty. |
Soda blasting crossed over into the automotive restoration field as somewhat of a miracle process, a misconception that had to be debunked. Although soda has its valid uses as a blast medium, it also has its own set of complexities and nuances that must be taken into consideration. | Soda blasting crossed over into the automotive restoration field as somewhat of a miracle process, a misconception that had to be debunked. Although soda has its valid uses as a blast medium, it also has its own set of complexities and nuances that must be taken into consideration. | ||
==Soda blasting procedure== | ==Soda blasting procedure== | ||
| − | Soda blasting is done with a high volume, low pressure wet or dry blasting machine. Soda cleans surfaces not by abrasion, like conventional blasting media, but by the energy released by the explosion that occurs when the soda particles contact the substrate. | + | Soda blasting is done with a high volume, low pressure wet or dry blasting machine. Soda cleans surfaces not by abrasion, like conventional blasting media, but by the energy released by the tiny explosion that occurs when the soda particles contact the substrate. |
==Soda blasters== | ==Soda blasters== | ||
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*Does not abrade or impinge substrate. | *Does not abrade or impinge substrate. | ||
*It's water-soluble, and can typically be washed down a conventional drain. | *It's water-soluble, and can typically be washed down a conventional drain. | ||
| − | *The soda blasting residue can be temporarily left on the substrate, as a [[rust]] inhibiting protective coating. | + | *The soda blasting residue can be temporarily left on the substrate, as a [[rust]]-inhibiting protective coating. |
*Sodium bicarbonate has a well-known chemistry, and is widely considered safe to use. | *Sodium bicarbonate has a well-known chemistry, and is widely considered safe to use. | ||
*You can soda blast lightly to leave the body filler intact, and then go over it again to remove all filler. | *You can soda blast lightly to leave the body filler intact, and then go over it again to remove all filler. | ||
| − | *No pre-cleaning required ( | + | *No pre-cleaning required (prior to blasting, traditional blasting media may require the surface to be thoroughly cleaned to remove salt, carbon, or grease). |
*Allows for easier detection of surface flaws. (Traditional abrasive media may peen cracks closed, or fill them with abrasive, whereas soda cleans out the cracks). | *Allows for easier detection of surface flaws. (Traditional abrasive media may peen cracks closed, or fill them with abrasive, whereas soda cleans out the cracks). | ||
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*Laborious, time-consuming steps required to prep parts after blasting. | *Laborious, time-consuming steps required to prep parts after blasting. | ||
*Only removes light flash [[rust]]. | *Only removes light flash [[rust]]. | ||
| − | * | + | *Because soda is so soft, it does not leave an anchor pattern. For reference, see this [http://www.reade.com/Particle_Briefings/mohs_hardness_abrasive_grit.html Mohs hardness scale abrasive comparison chart]. |
| − | * | + | *Paint manufacturers advise against its use. |
*Can't re-use the medium after blasting. | *Can't re-use the medium after blasting. | ||
| + | *Soda Blasting will not allow for a high silica count paint to adhere to it after process is complete. | ||
Overall, soda blasting is probably not the best choice for the hobbyist or do-it-yourselfer. | Overall, soda blasting is probably not the best choice for the hobbyist or do-it-yourselfer. | ||
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Soda blasting is frequently touted as an environmentally-friendly blast medium. | Soda blasting is frequently touted as an environmentally-friendly blast medium. | ||
| − | However, it's likely no more or less environmentally-friendly than media such as corn cobs | + | However, it's likely no more or less environmentally-friendly than media such as corn cobs, walnut shells, or crushed recycled glass, such as [http://www.trivitro.com/vitrogrit/vitrogrit.html VitroGrit]. Aggressively portraying soda blasting as "green" may qualify as [http://en.wikipedia.org/wiki/Green_marketing green marketing] or even borderline [http://en.wikipedia.org/wiki/Greenwashing greenwashing]. |
| − | + | The used soda medium can be screened or filtered, and washed. The water-soluble soda can typically go down a conventional drain, leaving only the blasted particles behind. However, soda blasting medium may contain various flow additives that are less environmentally-friendly. | |
==Published professional opinions on soda blasting== | ==Published professional opinions on soda blasting== | ||
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This opinion is expanded upon in [http://spi.forumup.org/viewtopic.php?t=156&mforum=spi this discussion in the Southern Polyurethanes forums]. | This opinion is expanded upon in [http://spi.forumup.org/viewtopic.php?t=156&mforum=spi this discussion in the Southern Polyurethanes forums]. | ||
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<blockquote> | <blockquote> | ||
''"We don't recommend sodium bicarbonate, because you can’t clean it out of the pores of the metal well enough."'' | ''"We don't recommend sodium bicarbonate, because you can’t clean it out of the pores of the metal well enough."'' | ||
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The use of soda blasting is thought to void the warranties of paint manufacturers. | The use of soda blasting is thought to void the warranties of paint manufacturers. | ||
| − | === | + | ===BASF=== |
| + | BASF does not have a position specific to soda blasting. If this method is used, after all residue is removed, standard substrate preparation procedures must be performed. | ||
| + | |||
| + | ===DuPont=== | ||
Awaiting response. | Awaiting response. | ||
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| + | ===Kirker=== | ||
| + | Reprinted with permission: | ||
| + | |||
| + | <blockquote> | ||
| + | ''Kirker does not encourage the practice of using sodium bicarbonate as a means of preparing a surface for refinish work, especially when we’re talking to the non-professional refinisher, which is probably how the majority of your readers would describe themselves.'' | ||
| + | <br><br> | ||
| + | ''Sodium bicarbonate is a very reactive material. Therefore, it is imperative to remove all residue before applying any coating over the blasted surface. Should any trace residue remain on the vehicle (most typically this occurs in seams, along trim molding, etc.), there is a good chance it could react with the coating which results in several product performance issues, the most common being delamination. More specifically, the sodium bicarbonate reacts with acids and/or other materials in the coating, which creates a source for carbon dioxide. As the CO2 gasses out from beneath the forming film, it can cause blisters in the surface which potentially give way to more serious delamination issues.'' | ||
| + | <br><br> | ||
| + | ''For removing existing finishes to prepare for refinish work, there are better options than soda including organic media like walnut shells and corn cob or more aggressive abrasives like polyester bead. All of this considered, soda blasting can be done correctly with very good results, however we feel that is outweighed by the extra prep steps required and greater potential for delamination issues.'' | ||
| + | <br><br> | ||
| + | --Matt Panuska, VP Sales & Marketing for Kirker Automotive Finishes | ||
| + | </blockquote> | ||
| + | |||
| + | ===PPG=== | ||
| + | Awaiting clarification and reprint rights. | ||
===Sherwin-Williams=== | ===Sherwin-Williams=== | ||
| − | The use of soda blasting does not nullify Sherwin Williams' | + | The use of soda blasting does not nullify Sherwin Williams' warranty. However, Sherwin WIlliams discourages its use. |
| − | + | Michael Pellett, a representative from Sherwin-Williams' Dallas Automotive Training Center [http://www.hotrodders.com/forum/once-all-wiki-soda-blasting-162700-4.html#post1160667 has stated]: | |
<blockquote> | <blockquote> | ||
''Like most paint companies, we have experienced poor results in the past regarding this process as a surface preparation step. We actively discourage our customers from utilizing this process by explaining the potential problems and offering other alternatives.'' | ''Like most paint companies, we have experienced poor results in the past regarding this process as a surface preparation step. We actively discourage our customers from utilizing this process by explaining the potential problems and offering other alternatives.'' | ||
</blockquote> | </blockquote> | ||
| − | For more detail, see the text of [[:Image:Sherwin-WilliamsWarranty.pdf| | + | For more detail, see the text of the [[:Image:Sherwin-WilliamsWarranty.pdf|Sherwin Williams warranty]]. |
===Sikkens=== | ===Sikkens=== | ||
| − | + | Does not recommend Soda Blasting | |
===SPI=== | ===SPI=== | ||
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===Valspar=== | ===Valspar=== | ||
| − | + | Does not recommend Soda Blasting. | |
==Related articles== | ==Related articles== | ||
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*[http://armex.com/CaseStudies/casestudy0102.aspx Armex automotive and aerospace case studies] | *[http://armex.com/CaseStudies/casestudy0102.aspx Armex automotive and aerospace case studies] | ||
| + | ==External resources== | ||
| + | *[http://www.chesapeakesodaclean.com/media/PDF/CSC-SodaBlast_Auto-Paint-Strip.pdf Soda Blast - Automotive Paint Stripping] | ||
[[Category:Body and exterior]] | [[Category:Body and exterior]] | ||
[[Category:Garage and shop]] | [[Category:Garage and shop]] | ||
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