The Clear Advantage of Chemical Immersion Cleaning

What the other processes fail to deal with...

The SPL cleaning process is unique. We welcome visitors to our site and are always happy to provide each of our customers with help and advice about the process itself and how best to prepare or modify each project to ensure the best results. It is paramount to us that our customers understand what they can achieve with our process and how it can be improved by following our recommendations and thinking it through.

A shell and its panels are complex and intricate. Each individual manufacturer offers a myriad of manufacturing design and techniques, some good and some not so good. By following our recommendations we believe that you can achieve the removal of the vast majority of the rust in your project far more than any other process available.

The close up shots demonstrate the extent of the rust that can be found within the hidden recesses of a bodyshell and why these areas cannot be dealt with by conventional cleaning or blasting methods.

In profile the gutter seam can be seen to be heavily corroded and whilst blasting the outside area of this section would make it look clean the rust will soon return from within the joint.	By identifying problem areas and simply providing some additional access holes for the ingress and drainage of the chemicals the SPL process can effectively clean nearly all of the rust from within the hidden areas. This section above demonstrates how searching and effective the cleaning process can be. Whilst we never guarantee 100% rust removal an area such as this could never be cleaned this effectively by any other method.	Areas with extensive corrosion damage can now be repaired before returning the shell or part to SPL for a final clean prior to the application of the chosen protection route.
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SPL Preparation and Corrosion Protection - Technical Process

The SPL Chemical Immersion Cleaning process can effectively remove the paint, grease, oil, underseal, filler, anti-flutter, adhesives and the majority of all rust from Panels, Parts and complete body shells. It has become widely accepted as a safe and vastly improved alternative to all types of media blasting methods. Media blasting is regularly associated with irreversible damage to the surface and structure of panels and parts and offers no solution to cleaning areas that cannot be reached with the blasting nozzle. One of the major drawbacks with any type of blasting is the problem of media and debris removal from the seams and box sections of the project leading to poor paint finish, moisture entrapment and ongoing issues with paint adhesion. Modern, more “gentle” blasting medias are generally considered to be unreliable for the removal of rust. With the SPL system rust is dissolved out on contact and an advanced corrosion protection in the form of electrophoretic coating can be applied to help prevent its return. Electrophoretic coating is again applied by immersion and is the same as that applied to 96% of the world new motor vehicle bodies and is widely regarded as the most effective anti-corrosion coating available due to its ability to coat the internal aspects of complex metal structures.

By carefully considering the construction and design of the shell or part the SPL process can help the restorer achieve the best possible results. We make no outrageous claim to remove 100% of the rust because it’s simply not possible. SPL are happy to discuss and advise on all aspects of the process and work closely with the customer to help them achieve the best results.

When considering your restoration we recommend the following route is followed for achieving the best results. For details on the cleaning and painting process please go to the bottom of the page.

Step 1. SPL Chemical Immersion - Full Clean

After the initial strip and clean the large majority of the rust will have been removed but there may be parts of the project that the process cannot penetrate and there may be heavy rust that may have to be removed manually. This gives the restorer a clear insight as to the extent of the required repairs.  

Step 2. Customer Repair and Modification

Once in the “bare steel” condition remaining rust can be readily dealt with and if necessary modifications can be made to improve penetration of the process for the second visit to SPL and the Electrophoretic coating process (if required). Welding is improved in the absence of the paint, grease and sealants and remaining rust is not hidden underneath primer paint as it would be when blasting and priming.

Step 3. SPL Stage two Re-dip

Rust that has occurred during the repair step is removed in the stage two re-dip (this is the rust removal and passivation stage detailed in the process overview below). Please note that if painted repair panels are applied to the shell then it may be necessary to go through the Full Clean again.

Step 4. SPL Electrophoretic coating

Again the restorer can make modifications ,some as simple as a 4mm hole, to the shell at Step2 to improve the penetration of the painting process. By carefully considering drainage and ventilation the performance of this stage can be much improved.

Step 5. Primer paint, minor repairs, seam seal and panel finish

The Electrophoretic coating is an industry standard anti-corrosion coating and as such all automotive approved re-finishing primers should normally be compatible with it. Customers are advised to seek assurance from the paint system manufacturer. Most paint manufacturers will only offer warranty if the paint systems are all from their own range and applied in accordance with their recommendations. Further advice on seam sealing methods and products should again be taken from the product manufacturers or a painting specialist.                                  

Step 6. Paint, cavity wax protect

Once painted, it is paramount to ensure that modern cavity and seam protection waxes/oils are applied. We recommend that the wax and seam protection is carried out at regular intervals by a professional applicator ensuring that, as well as the obvious underbody panels, the protection is applied to the pillars, windscreen surround, gutter joints and upper body panels (doors, bonnet, boot). well. Again further advice on these products should be sought from the manufacturers and or the application specialist.

Important note

Regardless of which route you choose to take the once the project has been through the initial clean it should be transported and stored in good dry conditions and should not be exposed to the elements. For further information please see the restoration guide page.

SPL Chemical Immersion Cleaning  - Process Overview

Paint rust and underseal removal

Stage 1. Decontamination
Heavy organic coatings including underseal, filler, mastic sealants, anti-vibration materials, adhesives, etc. are broken down and de-natured using an advanced dehydration process.
Stage 2. Organic Material Removal
The remaining organic compounds ie. paint, grease, oil and carbon, together with the remnants from Stage 1 are removed via immersion in an alkaline hydrocarbon solution for and then water rinsed. This leaves the mild steel free of any organic contaminants.
Stage 3. Rust Removal
Corrosion is now removed via immersion in a dilute solution of inhibited hydrochloric acid. Inhibitors prevent the acid from attacking the mild steel and will only allow it to break down the corrosion. The shell is tilted back-and-forth within the solution to improve penetration and help displace air locks. The solution will dissolve rust on contact. We cannot guarantee to remove 100% of all rust, especially if the corrosion is very heavy. Such areas will generally be apparent after the initial cleaning stage and should be dealt with manually. If these areas are difficult to reach, carefully considered modification may be required before further treatment. SPL are happy to advise.
Stage 4. Passivation Rinse
An advanced agitated alkaline neutralisation and passivation immersion process designed to give maximum penetration leaves the shell in a bright, preserved condition. This is then followed by a high pressure manual wash containing a neutralising preservative which is driven into the folds, seams and recesses of the component or shell. The shell is left with a bright and stable mild steel finish. We would recommend that the shell be weld repaired at this stage, before being returned to SPL for a repeat of stages 3 and 4 prior to painting. For more information on this, please see The SPL Restoration Guide.

The Electrophoretic Coating System

The Electrophoretic (e-coat) painting process is universally used on all modern vehicle shells, bracketry and panels. Designed to offer in excess of 1000 hours salt spray resistance* it is widely regarded as the best available anti-corrosion primer paint for mild steel. The shell and parts are immersed in all stages of cleaning, phosphating and painting and this provides excellent penetration into box sections and other areas that would be impossible to coat with a spray gun. The shell and skid are attached to a conveyor which carries them through the complete painting process. At each stage the shell is tilted forwards and backwards to reduce the formation of air pockets and improve solution and paint penetration.   Who uses E-Coat? The E-Coat Process (or KTL) is used by every major automotive manufacturer in the world. Over 95% of the worlds motor vehicles are primer protected with the cathodic electrocoat process.   Why do they use E-Coat? There is no better way to a add front line corrosion protection coating to a complex assembly like a vehicle bodyshell. Over 300 million vehicles have been coated with this process to date!   How is E-Coat applied? Shells and components are immersed in an 11 stage cleaning and pre-treatment process that deposits a corrosion resistant layer of Zn/Mn/Ni Phosphate. They are then immersed into the PPG Electrophoretic Epoxy Primer which is electrically bonded to the surface before being cured in an oven at 185ºC for 45 minutes leaving an impermeable, durable primer finish.

For more information on restoring your car with the SPL Process, please view our Restoration Guide.