Thread: How am I going to prep this body for paint?

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The problem I am addressing is that you stated you started the bodywork. If the bondo goes over rust, it will not allow the phosphoric acid to get to the rust to neutralize it.

Just use the acid, and then be very sure to resand before applying bondo. Metalprep leaves a coating on the surface. My experience is that you need to sand back to metal, or the bondo will not stick!

The other suggestion was to use self-etch primer, instead of metalprep. Many of the new fillers will adhere to paints. Just check it out with your paint supplier. He should know what works together.

OK, I got you now. When I said bodywork I meant the metal work. Dolly and hammer, patch panels, welding etc.

My plan was to use bondo over the epoxy primer.

How does that sound?

is this the stuff to use? I am doing the same thing to my engine compartment but will cover with por 15. Then do a final coat of paint over everything.



Detailed Product Description:

Metalprep®79 is a non-flammable multi-purpose phosphoric acid-based

cleaner and pre-paint conditioner for most metals. Application of

Metalprep®79 leaves the surface chemically clean and corrosion free.



Metalprep®79 can be used to deep clean and etch a metal surface prior

to paint or to prepare a surface for a subsequent chemical coating like

that produced by Galvaprep® SG on zinc and steel or Alodine®1201 on

aluminum surfaces.



Brush Application:

For light oxidation and corrosion removal, dilute one part Metalprep®79

with two parts water. For heavy oxidation and corrosion removal, dilute

one part Metalprep®79 with one part water.



Immersion Application:

For each 100 parts of bath, add 25 parts Metalprep®79 to 75 parts of water.



Spray Application using a 62-G Applicator:

Set dilution control on 3, allowing a mix of three parts water to one part

Metalprep®79.



Equipment:

Acid-resisting (rubber, stainless steel, or plastic) buckets, troughs, or other

suitable container should be used to hold the diluted Metalprep®79 cleaning

and conditioning chemical solution.



Ordinary steel pails may be used for a short period. Galvanized containers

should not be used. If production conditions warrant, troughs may be installed

to catch cleaner run-off for reuse.



Application:

A typical treatment time where Metalprep®79 is in contact with metal surface

is between one and two minutes. The Metalprep®79 should not be allowed to

dry on the metal surface or be permitted to re-oxidize prior to a thorough rinse.



Metalprep®79 is normally applied at temperatures between room and 120°F.

If drying occurs, rewet with the diluted Metalprep®79 prior to water rinsing.



A thorough rinse with clean water is necessary to remove both residual

Metalprep®79 cleaning and conditioning chemicals and oils that have been

lifted from the metal surface.



A clean surface is a "water-break-free surface". The rinse water sheets out

over the metal surface where oil will cause water to bead up. Chemical

cleaners will lift and break down oils on the surface of the metal and assist

in rinsing them from the surface of the metal.



Corrosion is generally the result of a chemical battery reacting on the metal

surface. In the presence of moisture, this corrosion can grow out over the

metal surface. Metalprep®79 cleaning and conditioning chemicals attack

the surface oxides and the corrosion battery. The result of this attack is either

the corrosion battery being removed or deactivated.



Blushing or yellowing on steel is often seen when using Metalprep®79 solution.

This chemical reaction is not injurious to quality, provided it is not rust or pits.



Blistering and corrosion problems are often the results of poor rinsing. Salts and

soils trapped under a paint film eventually lead to problems.



To aid in the removal of heavy oxidation or corrosion, heating and/or applying

the Metalprep®79 cleaning and conditioning chemical with an abrasive pad will

shorten the treatment time. Scotch-Brite pads are often used.



Metalprep®79 should not be used on a sand blasted part because rust will form

instantaneously. The rust, then formed, is harmful to quality. Paint soon after

the work is dry in order to prevent soils or rust from contaminating the prepared

metal surface.



Storage Requirements:

Metalprep®79 cleaning and conditioning chemical will freeze at 14°F. It is

recommended that the product be keep from freezing. However, should it freeze,

simply thaw it in a warm place and stir it prior to use.



Waste Disposal Information:

Applicable regulations covering disposal and discharge of chemicals should

be consulted and followed. Disposal information for Metalprep®79 is given

on the Material Safety Data Sheet supplied with this product. The processing

bath is acidic and contains phosphates. Waste treatment and neutralization may

be required prior to discharge to sewer.



Precautionary Information:

Before handling the product, the first aid and handling recommendations found

in the Material Safety Data Sheet should be read and followed. The processing

bath is acidic. Do not get in eyes, on skin or on clothing. In case of contact,

follow the recommendations found in the Material Safety Data Sheet supplied with

the product.

Sounds like the same way most metal preps are used.