Wednesday, 20 May 2015

How soon can you wax paint?

                One of the most often asked question (besides Leather care and Glass cleaning) and a subject that results in a great deal of confusion and misinformation regarding polishing or waxing re-painted panels.

Many paint company now say the 30-90 day recommendations are based on old paint formulations and the p-Sheets need to be up-dated in line with the latest paint specifications, although to my knowledge this has not been done. Most paints can have a paint protection product (wax / sealant/coating) applied within 36 – 48 hours of painting. However I would still abide with the manufacturers official recommendations

Part I - Applying a Polymer Sealant or Waxing Re-Painted Surfaces
a)       Polishing or Waxing Post-production Paintwork

1.        Refinish paint products, materials and paint drying methods are very different from original equipment materials (OEM) specified materials.

2.        This is only relative to re-painted surfaces that use a solvent –based paint. Modern environmentally friendly paint systems being utilized today are mostly water-base (EU- Sikkens, BASF, and Brillux), which evaporates quickly from the paint during the baking and drying process (US, only a limited number of painters are utilizing water-based pain, most are utilizing solvent based urethane)

3.        Unlike the oven baking process used by OEM painting t he process used in body shops is just a speed cure. Urethanes drying causes an exothermic reaction, that means they produce a small amount of heat as they cure, by adding  to the reaction, you accelerate it but if you don't it will just take more time but will eventually completely cure  on its own.

The majority of refinish paint is supplied by BASF DuPont, PPG and Sherwin Williams is 2K (2 component paint + activator) polyurethane systems; one component is polyisocyanate and the second is a polyol (acrylic or polyester polyol). Solvent-based paints (which still constitutes the majority of what is still being used, low solvent content VOC compliant) once the two components react they form a strong polymer chain. Or a water-based paint, much more prevalent in European imports than US mfg vehicles

Newly applied paint is soft, much softer than OEM paint,  dehydration (drying) is a different process from cross-linking; while newly refinished paint is about 90% cured within 24 hours, even with the help of a drying oven and various additives, and will fully harden (dehydrate) after 60-90 days dependent upon local environmental conditions

That distinctive smell of paint is actually dibutyl and diethyl phthalate out-gassing- two very volatile compounds

New paint needs to outgas for approximately 90 days (i.e. the solvents need to evaporate) if this is hindered by an inappropriate product application the clear coat may form a 'hard film' on top and the clear coat matrix may remain 'soft'. Most product data sheets (P-Sheet) state paint will air dry in 12 hours to buff and take 16 hours to fully dry.

Automotive paint is classified as a semi-permeable membrane; some chemicals, especially solvent based will penetrate a paint surface easily, others will just remain on the surface. A solvent or oil solvent emulsion will permeate the paint and fill the molecules causing them to swell. This will have an effect on the mechanical strength effecting both the paints tensile strength and elasticity

Current 2k (2 component paint + activator) polyurethane systems use chemical reactions to cross-link the clear-coat. Some body shops will oven cure them at approx 65.oF for 30 minutes and air dry over night or use an accelerator catalyst. Regardless, they still need to time for the solvents to evaporate (outgas) from the finish. By not allowing this process can create solvent-pop ‘like ‘fissures of the paint film and other issues.

During this period, using waxes or sealants that use a solvent as their carrier system should not be used since the solvents permeate the paint and soften it and if the wax or sealant contains abrasives, it can cause micro marring on the softened paint. The best products to use during this period are therefore water-based systems that are both solvent and abrasive-free.

Most paint shops use 10-20% more isocyanate component (hardener) than the polyol component. The reaction between these two (isocyanate and alcohol) is fairly rapid and that accounts for the 90% curing rate of the refinish paint within 24 hours. That leaves about 10% unreacted isocyanate, some of these isocyanate groups slowly react with moisture (hence the term moisture cure) and form amine groups (releasing CO2).

The newly formed amine groups rapidly react with isocyanate groups to form urea or polyurea, which is much harder than polyurethane adding solvents to the paint, hindering this reaction, while water-based products can help the (moisture) curing process.

Professional painters add chemicals; accelerants and compounds to their paint mix prior to painting to improve flexibility, reduce paint imperfections, increase hardness, and improve gloss and some body shops heat it in a paint oven to harden the ‘shell’, it doesn’t reduce cross-linking times (this process is both temperature and time dependent) But I would suggest waiting for approximately ten to fifteen days before any abrasive product application, which should be more than sufficient time to enable paint off gassing and aerobic curing

a) When a body shop wet sands and buffs out a newly painted panel they will hopefully polish out any sanding scratches, unfortunately this is not usually the case. Polishing paint that is at least 24 hours old is perfectly fine.

As a conservative estimate I would suggest waiting for approximately ten to fifteen days before any abrasive product application, which should be more than sufficient time to enable paint off gassing and aerobic curing

Unless you are a very experienced detailer I would strongly advise against the use of heavily applied pressure and overtly abrasive products as they behave more aggressively on soft fresh paint. I would suggest you allow the fresh paint to fully cross-link (cure) before you attempt to remove any surface imperfections

b) Automotive paint is classified as a semi-permeable membrane; it has both tensile strength and elongation (elasticity) newly painted surfaces are soft and full of out gassing solvents, resin binders and additives, as well as and water. Polish contains solvents, which soften the paint film, kinetic surface friction and applied downward pressure transfers its energy into heat / torque (force to rotate an object about an axis);

c) Which causes the soft paint film to become thinner by elongation and the pad rotation to transmit shear stress (torque= Force (radius) torque is twisting force, which could result in the alteration of the paint films bond between its substrate, causing it to delaminate or tear?   

d) The heat makes the gasses expand (pV = nRT) the expanding gases go through a phase transition (change in density) and to relive this increased pressure they (a) rupture the paint film surface, causing small fissures (similar to solvent pop)

e) The heat may cause the gaseous vapours to expand, but not enough to break through the hardening clear coat.   Once the vapour has evaporated, it may leave a void between the basecoat and the clear. 
Therefore you have a cloudy spot where the clear and base is no longer adhered together. If this is the case, the clear coat will delaminate in the future.

f)  Once the outgas process is complete automotive coatings (paint) becomes a semi-solid permeable membrane, Being a polymer (elastomers) it remains flexible while retaining its tensile strength, to enable it to expand and contract to follow temperature fluctuations (elongation) kinetic friction and its associated heat can cause a rapid temperature rise (i.e. initial surface temp 80.oF, heat attained with a cutting foam pad at 1,100 RPM for approx. ten seconds is approx. 104.oF) the paint temperature can be checked by utilizing an instant read-out infra-red ‘gun’ thermometer, paint surface ‘spot’ temperature should be limited to 110.oF <

In accordance with the Society of Automotive Engineers (SAE) a temperature of 115.oF will cause the urethane clear coat to soften and the foam pad will cause scratching that is forced deep into the clear coat.

Also be aware that plastics and those surfaces that have flex agent additives have a different thermal rating and will be negatively affected by applied heat very rapidly.

Fresh paint safe glaze’ - while a paint is cross linking,  using solvent- based waxes or sealants is not ideal since the solvents penetrate the paint and soften it and will interfere with the outgas / cross linking  process.

The common ingredients in a’ fresh paint safe’ glaze are: water, glycerine or  mineral oils(to produce a high shine)  and a mild abrasive Kaolin (China clay) to burnish the surface and produce a gloss, some polymers are also formulated as ‘fresh paint safe’ for the same reasons

The application of a specific ‘fresh paint safe’ water-based or polymer type product, Zaino Polishes (exclude the use of either Z1 or ZFX™) Optimum Car Wax is water-based and is safe on fresh paint, or use Presta Fast it’s a liquefied paste wax manufactured with premium, natural and synthetic ingredients. This unique wax can be applied over 24-hour old clear coat and single-stage finishes without risk of die back, because it creates a breathable film that permits solvents to cross the wax film. Allow an ‘initial gas off’ (evaporate) /cure aerobic process of 7 days before application

These products are completely safe for any fresh paint system as they allow the solvents in a water-based paint to outgas / aerobic cure process and provide some protection for any type of paint surface. After thirty days (30) the paint surface can be protected with a regular polymer sealant and/or Carnauba wax.

1.        Both DuPont and PPG recommend a 90 day period whereas BSAF advise 30 days; but any recommendation is dependent upon what paint, hardener, drying system, additives etc were used, the body-shop / paint manufactures know their products; seek their advice Paint manufacturer have specific technical guidelines (see ‘Product Sheet’ or P-Sheet) on how to use their products to affect a warranted spot/panel/ repairs or a full repaint. This preserves both the paint manufactures and factory warranty (if offered)

2.        Abrasive polish should be avoided until the paint has cured (an abrasive polish will not necessarily harm the soft new paint but unless it’s absolutely necessary I would avoid it)

3.        Vehicle washing is encouraged but avoid car wash concentrates that contain any harsh detergents, alkali, acids, wax (recommended products- Zaino Z-7™ Show Car Wash, Groit’s Car Wash) also avoid car washes that uses a high-pressure spray, harsh detergents  or brushes
4.        Don't use a car cover until the paint is fully cured?

5.        A paint film surface is a delicate thin coating easily dulled and very easily scratched, so choose carefully the advice you listen to and most importantly what advice you act upon.

6.        Some Carnauba wax contains paraffin wax, which effectively ‘seals’ the paint surface more than a polymer due to its formulation.

7.        The use of water-based products is highly recommended

Part II - Applying a Polymer Sealant or Waxing OEM Paint

b) Polishing or Waxing Production (OEM oven cured) Paintwork

Original equipment materials (OEM) specified materials are very different from refinish paint products and materials

One of the most often asked question and a subject that results in a great deal of confusion regarding polishing or waxing OEM paint, Once you brought a new vehicle “How soon can I wax my car”?

To find out how long ago your vehicle was painted; check the driver's side door jamb, a sticker should give the month and year the vehicle left the plant. Paint curing process; new cars go through the painting and baking process without any of the rubber, plastic, and cloth components installed. This is why they can expose the cars paint to such high temperatures, these high temperatures and special paints used at the factory level ensure the paint is fully cured by the time the car leaves the assembly line.

Original Equipment Manufacturer (OEM) paint is cured at high temperatures; OEM paints are cured in a paint oven at around 320. °F (160. °C) for 20 minutes, in multiple oven zones where the paint is baked with radiation and convection heat, or infrared so that 90-95% of the paint systems out gassing has taken place, the additional 5-10% will cure within 2-3 days, it will probably be stored for one or two days before transportation, it is then shipped or transported over the road (OTR) to a dealership and most likely be on the lot for a few weeks or more. So the vehicle’s paint can be waxed as soon as you take delivery.

By not applying some sort of paint protection soon after purchase the customer is actually damaging the paint surface instead of helping it. Salesmen that advise a customer not to wax a car for 3-6 months are relying on old paint methods and are misinformed about the latest paint technology. The newer paints are catalyzed (a chemical reaction that cures the paint) lacquers and enamels needed an extensive time for the solvents to release, with modern water-based or reduced solvent content paints this is not necessary.

This is a huge problem in dealerships because customers tend to take the advice offered by a salesman who usually knows nothing about paint, rather than a trained paint professional. This goes a long way to understand why fairly new vehicles paint surfaces are in such bad shape even after a relatively short period of time.

Twenty years ago, cars were typically painted with lacquer or enamel paints. These were single stage paints, with a large volume of solvents that needed to escape before the paint would fully dry. These paint systems dried from the outside in. The paint would look and feel dry, but the layers underneath could still be a bit wet and soft because all the solvents in the paint had yet to escape. Therefore, if wax was applied to the paint surface before it was fully dried, there could be problems. There could have been solvent pop, which occurs from solvents pushing up through the paint and the wax, giving the paint a crater-like appearance.

The paint could also have “died back” or faded a bit because of the trapped solvents clouding the paint. Also, solvents that did not escape would leave the paint softer and more susceptible to scratches and blemishes.

Twenty years ago this was correct; you should not to wax a new car with these paint systems. However, that was 20 years ago and no longer applies with today’s base-coat/clear-coat paint systems.

I would like to think that these articles become an asset to anyone who is new to detailing and to professionals alike, as well as industry experts who seek to advance their knowledge.

I hope the above article was informative. By having some understanding of the ‘What’ and ‘Why’ as well as the ‘How’ along with a little science to help you understand how the chemicals we use react, you can achieve the results you desire.
I would appreciate it if you would share this article as it helps other detailers further their knowledge.
Questions and/ or constructive comments are always appreciated.

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