REPAIRING PPA 571 COATINGS

Whilst Plascoat PPA 571 coatings provide a high degree of protection to metal substrates it is appreciated that damage can occur in the transportation, fabrication and on-site installation of large and heavy items.  Items such as lampposts may also be subject to vandalism.

In the event of damage occurring to items coated in Plascoat PPA 571 it is essential that a proper repair is carried out in order to obtain the full level of protection that Plascoat PPA 571 can provide.  There are a number of systems that Plascoat Systems can recommend for such repairs.

Choice of Repair System

If accidental damage occurs during or immediately after the coating process, Plascoat PPA 571 powder can be poured carefully onto the damaged area and fused with localised heat. As long as the metal and surrounding coating area are hot enough, the fresh powder will fuse with the existing coated film and cover the defect with a new, pinhole-free film. If the metal temperature is no longer sufficient to allow this to happen, the part can be re-heated with care.

If the damage occurs after the metal part is cold, or if the damage occurs much later, the affected area must be warmed with a heat source, such as a naked gas flame or hot air gun. The metal area to be repaired has to reach the fusion temperature of Plascoat PPA 571. Some fresh powder can then be applied. If the residual heat is insufficient to fuse the new powder completely, the item must be re-heated slightly and with care. It is important to avoid overheating the fused coating around the repair point since a degradation of that coating may occur.

Minor repairs to surface scratches can be made using a hot air gun. A few light passes with the hot air gun will restore the surface to a high gloss, smooth finish.

However, the repair of damaged areas with "repair strand" is the preferred method.  For quicker repairs Interthane 990 is suitable but it provides a relatively thin coating. 

To obtain a more protective and cosmetic repair to more serious damage, Plascoat would recommend a combination of car-body filler and Interthane 990.

Surface Preparation

Before any repair is carried out any loose and damaged coating should be removed with the aid of a sharp knife.  It is essential that the surface to be repaired is free of rust, dirt, grease and other contaminants.  Rust and dirt should be removed using an abrasive cloth and the area cleaned with a suitable degreasing agent such as cellulose thinners or White Spirit.

Once the surface to be repaired has been prepared the repair can be carried out by one of the three methods detailed.

A.        With Repair Strand

Repair Strand is available from Plascoat Systems.

PTFE pressure rollers and suitable heat sources can be obtained from Welwyn Tool Co. (UK Tel: 01707 331 111) or Stan Mech agencies Inc, 2586 Dunwin Drive, Unit 7, Mississauga, Ontario, L5L 1J5, Canada.

An alternative heat source is a paint stripper gun such as the 'Black & Decker KW1600' which operates at 1400 watts. 

Procedure

1. Preheat the damaged area and the surrounding area with a gas soldering iron or a hot air gun until the edge of the coating surrounding the damaged area becomes softened.

2. Preheat an end of the Plascoat PPA 571 repair strand with the heat source until it has started to melt and apply it to the hot damaged area.  Continue to apply molten material from the repair strand to the damaged area until sufficient material has been deposited to fill the damaged area.

3. Using a PTFE roller, smooth out the molten material to fill the damaged area.

4. Apply further strand and smooth out as necessary.

5. Using the heat source carefully re-apply heat to the repaired area to regain the gloss  level.

B.       With Interthane 990

Interthane 990 produces a dry coating thickness of 30 microns and is touch dry in 90 minutes.  If a second coat is required this should be applied at least 6 hours later.  

Read and abide by the instruction on the Material Safety Data sheet available from Akzo Nobel (International Protective Coatings).

Interthane 990 is available in a wide colour range via the Chromascan system.  It is a two component acrylic polyurethane finish.  Details of your local supply can be obtained from International Protective Coatings, World Centre, P.O. Box 20980, Oriel House, 16 Connaught Place, London, W2 2ZB England. 

Phone +44 20 7479 6000. Fax +44 20 7479 6500 or visit www.international-pc.com.

Procedure

1. Mix the two-pack system according to the manufacturers instructions and health and safety data.

2. Apply by brush.

C.       With car-body filler and Interthane 990

Car-body fillers can be obtained from local automotive suppliers.

For information on Interthane 990 please refer above.

Procedure

1. In addition to the surface pre-treatment recommended suitable preparatory agents normally recommended for car-body filler application such as rust preventers can be applied to the bare metal surface.

2. Apply to the damaged area a sufficient amount of car-body filler to fill the damaged area and smooth out the filler.

3. When the car-body filler has set it can be smoothed level to the surface of the Plascoat PPA 571 coating with an abrasive cloth.

4. Apply Interthane 990 as in procedure B.

Note:  Magic Bond epoxy putty can be used instead of car-body filler.  This can be obtained from ITW Devcon, Brunel Close Park Farm, Wellingborough, Northants, NN8 6QX.

Health and Safety

Care should be taken when using sharp knives and heating equipment.  The safety recommendations of all suppliers of materials and equipment mentioned in this document must be followed. 

Precautions must be taken to avoid skin and eye contact with molten PPA 571.  Reference should be made to Plascoat Systems Health and Safety data sheet HS506, available on request.

Plascoat Systems can accept no responsibility for accidents arising from the use of equipment or materials not manufactured by Plascoat Systems.

25/07/2002

-- More information on PPA 571 -- Plascoat PPA 571 Data Sheet Application and fusion of PPA 571 Application of PPA 571 over galvanised steel Oxidative stability of PPA 571 Chemical Resistance of PPA 571 PPA 571 - Fire and fume certificates PPA 571 - pre-treatment PPA 571 - processing emissions Removal of PPA 571 coatings Health and Safety Data Sheet Water and food contact approvals Recommended pre-treatment over galvanised steel Recommended quality control procedures Specification for the coating of steel cable supports PPA 571 colour range Repairing damaged coatings Comparison of PPA 571ES and Polyester How long do PPA 571 coatings last...? The coating of cast iron Gassing when coating over galvanised steel Plascoat PPA 571 - Overspraying with Thermoset Powders Plascoat PPA 571 ES processing conditions Electrical resistance of PPA 571 Flame spray repair methods Procedure for ascertaining coating weights Flame spraying of Plascoat materials Plascoat PPA 571 environmental information PPA 571 colour card Removal of graffiti from PPA 571 coatings Plascoat PPA 571ES over Oxsilan pre-treatments

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