Editing Phosphoric acid as metal pretreatment
Line 7: | Line 7: | ||
==Brands of phosphoric acid-based metal pretreatments used for automotive work== | ==Brands of phosphoric acid-based metal pretreatments used for automotive work== | ||
===Ospho=== | ===Ospho=== | ||
− | Ospho is advertised as "a balanced formula of Phosphoric acid, Sodium Dichromate, Surfactants, and Extenders." According to Ospho's | + | Ospho is advertised as "a balanced formula of Phosphoric acid, Sodium Dichromate, Surfactants, and Extenders." According to Ospho's, as detailed in [http://www.hotrodders.com/forum/ospho-factory-response-173513.html#post1234300 this post]: |
#Once Ospho has dried, there is no longer any acid on the surface to react with paint. | #Once Ospho has dried, there is no longer any acid on the surface to react with paint. | ||
− | #Ospho is totally neutralized by reaction with both the rust particles and the steel underneath. | + | #Ospho is totally neutralized by reaction with both the rust particles and the steel underneath. A quick water rinse will remove any dust-like reaction particles. |
− | #Because Ospho is water-based, the water can hide in nooks and crannies, causing adhesion failure of primer | + | #Because Ospho is water-based, the water can hide in nooks and crannies, causing adhesion failure of primer. |
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
==Naval jelly== | ==Naval jelly== | ||
Naval jelly is considered safer to use than traditional liquid phosphoric acid metal pretreatments. For rust removal on body panels, the naval jelly is kept wet. Paint failures from phosphoric acid are thought to be caused by wiping on the acid, and letting it dry. | Naval jelly is considered safer to use than traditional liquid phosphoric acid metal pretreatments. For rust removal on body panels, the naval jelly is kept wet. Paint failures from phosphoric acid are thought to be caused by wiping on the acid, and letting it dry. | ||
− | + | ''need details here on exact concentrations, and use of naval jelly vs. traditional phosphoric acid treatments'' | |
− | + | ||
− | + | ||
==Reasons for using phosphoric acid== | ==Reasons for using phosphoric acid== | ||
*Inexpensive. | *Inexpensive. | ||
− | *[[Media blasting]] has its own set of drawbacks | + | *[[Media blasting]] has its own set of drawbacks. |
− | *If used perfectly, it works | + | *If used perfectly, it works perfectly. |
− | + | ||
− | + | ||
==Reasons for not using phosphoric acid== | ==Reasons for not using phosphoric acid== | ||
+ | *Metal pretreatment manufacturers are economically incentivized to recommend their products. A better point of view might be obtained from the manufacturer of the product that is destined to go on top of the pretreatment. | ||
*Even a very low failure rate is economically disadvantageous, especially in light of the value of a professional paint job, and the labor required to fix a failure. | *Even a very low failure rate is economically disadvantageous, especially in light of the value of a professional paint job, and the labor required to fix a failure. | ||
Line 49: | Line 32: | ||
*A manufacturer's tech sheet may specifically advise against using an acid pretreatment. Always follow the tech sheets for the products you are using. | *A manufacturer's tech sheet may specifically advise against using an acid pretreatment. Always follow the tech sheets for the products you are using. | ||
− | + | *Amateurs and [[First paint job|first-time painters]] are more likely to make errors. Phosphoric acid pretreatments must be used meticulously, and are thus not recommended for beginners. | |
− | *Amateurs and [[First paint job|first-time painters]] are more likely to make errors. Phosphoric acid pretreatments must be used meticulously, and | + | *It has to be used perfectly. This may work in a controlled environment (industrial, manufacturing, etc.), but not for a home hobbyist. |
==Specific paint and primer failures caused by phosphoric acid pretreatments== | ==Specific paint and primer failures caused by phosphoric acid pretreatments== | ||
Line 56: | Line 39: | ||
*Epoxy cracking. | *Epoxy cracking. | ||
− | ==Published | + | ==Published epoxy primer and paint manufacturers' positions on the use of phosphoric acid pretreatments== |
− | + | ||
− | + | ||
− | + | ||
− | ' | + | |
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
− | + | ||
===Southern Polyurethanes, Inc.=== | ===Southern Polyurethanes, Inc.=== | ||
− | *[http://www.southernpolyurethanes.com/tech%20sheets%20new/epOXY%202006.pdf Southern Polyurethanes | + | *[http://www.southernpolyurethanes.com/tech%20sheets%20new/epOXY%202006.pdf Southern Polyurethanes]: |
<blockquote> | <blockquote> | ||
''"NEVER use SPI Epoxy over a Soda Blasted vehicle, Acid Etch/Wash Primer, Rust Converter or other Metal Treatments. NEVER!"'' | ''"NEVER use SPI Epoxy over a Soda Blasted vehicle, Acid Etch/Wash Primer, Rust Converter or other Metal Treatments. NEVER!"'' | ||
Line 76: | Line 49: | ||
==Use of phosphoric acid in an industrial setting== | ==Use of phosphoric acid in an industrial setting== | ||
− | |||
− | + | ||
− | + | ||
− | + | ||
==References== | ==References== | ||
Line 89: | Line 59: | ||
*http://www.skybryte.com/index.html | *http://www.skybryte.com/index.html | ||
*http://www.ospho.com/data.htm | *http://www.ospho.com/data.htm | ||
− | |||
− | |||
[[Category:Body and exterior]] | [[Category:Body and exterior]] |