Foam Pads 101 Foam Pad Dependency All abrasive polishes are ‘foam pad and applied pressure dependant’ as far as their paint correction abilities are concerned. If we consider the Lake County (LC) White foam (50 PPI) polishing pad as the baseline; any polish used will derive help from the abrasive abilities of the foam. Then consider the LC Blue (70 PPI) finishing pad has no abrasive ability and will contribute nothing to the cutting capability of a polish. What is derived from this is that a polishes abrasive ability can be ‘fine tuned’ by using different combinations (abrasiveness) of polish and foam (the same thing is true of wool pads) and of course differing the amount of downward pressure (10-15 Lbs is the usual range) applied will also have an effect on the abrasives capability Different pad / product combinations a) Base pad / product (least abrasive pad / product) if this combination does not provide the desired results, increase the aggressiveness of the technique or product selection. b) Step-up 1 - using the same pad with a more abrasive product c) Step-up II – use a less abrasive pad and the same product as used in step-up I d) Step-up III- using the same pad with a more abrasive product Foam Pad Size (Area and Applied Pressure) Smaller pads in general will offer you more control with any buffer, as it can reduce the tendency for the buffer to skip on the paint surface. Smaller pads also make it easier to manoeuvre in tighter areas and closer to trim pieces. Assuming equal speed, radius and foam compression (50% - 15 pounds of force applied) the difference between 4- inch and 6 - inch pads is their different surface area = π (r2) (4-inch = 12.46 sq.ins / 6-inch = 28.26 sq.ins) and therefore surface kinetic (or dynamic) friction applied and surface pressure applied 4-inch = 3.75 lbs per sq.ins. 6-inch = 2.5 lbs per sq.ins. Pores per inch (PPI) As an example you could purchase two seemingly similar pads based upon their PPI rating, but one pad may have thicker walls between each pore, be made of softer material, feature a reticulated or non-reticulated foam structure (basically open or closed cell), or simply be a thicker (1.25 or 0.75-inch) foam, which can affect the machine's movements. Compressible, open cell polyether polyurethane reticulated foam is usually specified by pores per inch (PPI).The greater number of pores per inch generally equates to foam that is softer; and has less abrasive ability, less density, more porosity and easier compression. There is no recognizable standard for the abrasive abilities of foam, other than a colour assigned; most foam manufacturer’s that supply foam to detailer’s product vendor assign their own colours to donate abrasion. On this basis a PPI rating allows abrasive ability comparisons between different foams Remember the flatter and more uniform you make the surface, the greater the light reflection .While most enthusiasts understand this principle when applied to polishing, the same is true of finishing. The more uniformly you apply the final wax or sealant, the greater the shine Scale 30 – 100 PPI • Abrasive Cutting Foam (40 pores per inch) • Medium Cutting Foam (50 pores per inch) • Light Cutting Foam (60 pores per inch) • Finishing Foam (70 pores per inch) • Fine Application (80 pores per inch) • Ultra-Fine Finishing (100 pores per inch) Grit Numbers Sandpaper or finishing paper is the most common item from a larger group of products known as "coated abrasives" i.e. Aluminium oxide. When talking about "grit" is a reference to the number of abrasive particles per inch of finishing paper (sandpaper). The lower the grit the more abrasive and conversely, the higher the grit number the lesser (smoother) the finishing paper When talking about abrasive finishing paper, "grit" is a reference to the number of abrasive particles per inch of paper. It eliminates the risk of deep sanding scratches by providing a uniform grit size. The lower the grit numbers the rougher the paper and conversely, the higher the grit numbers the smoother the paper. This makes sense if you imagine how small the grit particles on a 1000-grit finishing paper would need to be to fit into a 1" square. Grit finishing paper is referred to by the size of its abrasives (i.e. 1500-grit paper) the grit you use depends on what you are trying to do. a) Polishes have a grit number) most polishes will state the level of scratch removed by stating grit numbers i.e. will remove 2000 grit scratches caused by using 2000 grit finishing paper b) Foam Pads are also rated on a grit number, that is to say the scratches they will remove after using grit finishing paper along with a similarly rated polish (i.e. 2000 grit rated pad and polish will remove the marks left after using 2000 grit finishing paper) Once you have identified the scratch ‘grit’ marks you can match a polish and a foam pad (i.e. 2500 grit marks, require a polish that is capable of removing 2500 grit (number) marks, matched with a suitable cutting pad (e.g. Menzerna Power Finish (PO203S) this is a one-step scratch remover polish that will remove 2500 grit, matched with a LC White Light cutting foam pad 1. 1000 < grit Heavy - (Compound) levels and removes heavy defects 2. 1200 grit Heavy - levels moderate to heavy defects 3. 1500 grit Medium - levels light to moderate defects 4. 2000 grit Moderate - levels light defects and removes hazing 5. 2500 grit Light - levels swirl marks, light defects and removes hazing 6. 3000 grit Fine - very minor corrective ability, burnishes paint to high gloss General Rules 1. Porter Cable 7424 random orbital polisher; the limiting factor to pad size is the actual power of the machine. Using larger pads on these machines actually reduces the amount of polishing power due to the surface resistance of the pad, which will cause the motor to slow down or stall. Conversely using a smaller pad will increase the power available by reducing the surface resistance by concentrating motor power on a smaller area. 2. With smaller pads you gain increased control and manoeuvrability. Smaller pads generate more kinetic friction (and subsequently, increased heat) with a PC, which breaks down polishes by generating energy (and applied pressure) over a concentrated area. The random orbiting motion of the PC generates the most power in the centre of the pad (i.e. area of a 6.5 – inch pad is 33 – square inches compared to the area of a 4 – inch pad, which is 12.5 – square inches) This additional pressure / cutting power will facilitate the removal of deeper imperfections 3. The opposite is true with rotary buffers. The speed of the outer edge of a smaller (radius) pad is slower than that of a larger (radius) pad. This helps reduce the amount of friction generated, which makes polishing tighter areas much safer. 4. Do not use the same pad to apply differing products as cross contamination will reduce the effectiveness or completely negate their purpose altogether. A new or freshly cleaned pad must be used with each type of car care product. 5. Water will increase the abrasiveness of a polish; but unlike wool, a foam pad has no fibres to twist, bend, and reshape, therefore helping to loosen the abrasive, so water tends to cause abrasive-clumping, which is detrimental to its performance 6. There is no recognizable standard between manufacturers that use colour as an identification of the abrasiveness of a foam 7. Apply pressure to the foam; if it springs back the pad is fine. If it stays compressed the foam core is damaged and it’s time to replace the pad. Priming / Seasoning Pads Using water - if the pad is not kept clean (especially when using a water spritz), the abrasives and paint residue tend to pack onto the surface of the pad or into the membrane structure, and stay there. The main reason for this is typically, a lack of centrifugal motion, because there is less high speed rotation of the pad, so the residues tend to stay where they are compared to using the same setup with a rotary. Most quick detailer or a pad conditioner are usually formulated with silicones, oils, waxes, polymers, gloss enhancers, which will negatively affect the polish lubrication ( an exception is Meguiar’s Final Inspection Spray, diluted 1:1 distilled water ) spraying water while polishing can cause the foam pads abrasives to aquaplane, as water for all intents and purposes is incompressible, so that the pad and the abrasive don’t have actual surface contact, thereby negatively impacting the abrasive abilities of polishing process. Spread the polish / compound over the pad evenly and ensure it is absorbed into the foam, then spread that polish onto the pad by hand until it becomes 80% saturated. To apply to the paint surface; lightly raise the back of the machine so you are working with the top 1/3 of the pad. After polishing for a minute or two the pad will become more evenly saturated Once the pad has been seasoned (pad is saturated with product) you can reduce the amount of polish / compound applied to the pad for subsequent passes; dependent upon what you're trying to accomplish. If you use too much polish or compound the oils will cause the surface to become over lubricated, which will negatively impact the abrasive abilities. A good rule of thumb; you should always be able to see the individual cells on the pad. To apply to the paint surface; lightly raise the back of the machine so you are working with the top 1/3 of the pad. After polishing for a minute or two the pad will become more evenly saturated with product and actually become softer from friction induced heat build-up (seasoned). At this point, you can safely transition from a tilted up to a flat polishing position. Every time you put a fresh pad on your machine (and this should be done often) you should prime and then season it for a minute or two before "flat" polishing. Some advantages to pad priming: • Increased cutting ability • Better surface finish • Eliminates carrier system (solvent) flashing problems • Surface is more evenly polished and polisher is easier to control When you prime entire pad, by spreading the abrasives uniformly and by keeping the pad flat thus ensuring constant paint / polish contact it becomes similar to a piece of wet-sanding finishing paper, the oils in the polish provide the lubrication (like the water does in wet-sanding) Note – clean and / or replace pads as often as is necessary; a clean seasoned pad will enhance the abrasive abilities of the compound / polish and make the process not only more efficient but less time consuming. Extracts are from a series of unbiased Detailing Technical Papers, a library of educational materials that has become the #1 reference for car care on the Internet Chances are you'll learn something about detailing if you read any of these; although these articles will not improve your detailing skills, lead to a successful business or change your life. Applying what you learn from it, however, will. That's where your commitment comes in - you need to make a commitment to yourself right now that you will take action on what you learn. © TOGWT ™ Ltd Copyright 2002-2010, all rights reserved
