Guide to scratch repair using the cut/shave technique…. In this guide you will find out the difference between wet sanding scratches and using the cut technique, the effect of the cut method and its advantages, although you may not automatically think of any advantages but they are there, as you will learn later….. The Titanium Block At around an inch square and about 5mm thick this little block could be the saviour to so many awkward scratch related defects….Titanium is one of the hardest metals known to man and once this little block has been engineered and sharpened it will stay sharp, this is not only limited to one cutting edge but eight in total…. Mine is 9 yrs old and still as sharp as it was the day I first received it…. Getting started is a simple matter of following the basic rules of touch up, firstly ensure there is no dirt, grime, grease or even wax residue present in the scratch itself, the way I do this is a thorough wipe down with IPA, if there is any rust present this needs to be dealt with accordingly by using a rust inhibitor to eat away at the rust, not too sure how effective this stuff but at least its got you started, primer is necessary in this case, depending on how deep and wide the scratch depends on the thickness of the brush to be used, a couple of coats of primer should suffice, should you overlap the primer at this stage and as it is still wet wipe this away from the edge of the scratch…. Now, onto the colour coat, most touch up pens bought from dealers will be a better match than those from your local high street motor factors, you all know which one, my preferred choice though is my local paint specialist, if the car is non metallic then a straight colour in either high solid or cellulose can be mixed for me, I tend to go for the HS as this has a better cutting surface as it flows a little easier, however I do get cellulose mixed up as well for other methods of scratch repair, this is also the case with metallics, the colour is solvent basecoat and the clearcoat is HS and Cellulose, obviously hardener has to be present for the HS. Once you have chosen the correct brush size do not get the temptation just to whack a thick coat on and have done with it, build the coats up on a basis of “the thinner the coat the better the finish” this also allows solvents to escape more evenly which in turn allows the paint form more evenly, this must be allowed to dry, not completely but sufficient enough to hold a further coat, if you are using basecoat you must also allow for the clearcoat that needs to be applied, once the touch up process is completed it must be left to fully cure, otherwise the block will start to snag, likewise should the process be wet flatting at this stage you will be left with micro bubbles in the paint finish, ultimately either of these will affect the finished result, the way I used to dry them was an infra red heat lamp but not cost effective unless it’s a day to day thing, halogen lamps create enough heat to cure the paint but do take longer…. Now, onto the cutting, the repaired scratch should have paint protruding, slightly over the edges of the scratch, not too heavy, if the paint does look heavy then leave it a while longer…. Taking the block hold it against the panel at an angle of around 30-40 degrees, basically your finger should be in contact with the panel, now slightly move over the top of the scratch removing fine shavings, in some cases this one pass is sufficient but in heavier finishes it could take upto 4 or 5 passes to get the repair flat, being careful not to snag the edge of the block on the surrounding paint area, this will result in slight scratches which should polish out in the same repair polishing period, unfortunately some of these snags have caused deeper damage which then need either repairing or indeed wet sanding. Having finished the cutting you will be left with a completely level surface repair requiring NO flatting, this can either be polished to a finish now or after the rest of the correction has been done, if any. Such is the high standard of the scratch repair little polishing should be required, I find that on a simple scratch repair with no other work be carried out a Farecla black finishing pad with Dodo juice Lime Prime is sufficient to bring a finish to the repaired area. The pictures below show the scratch repair on a carbon black BMW M3…. Scratch before repair having been touched in by the customer... During... And after the cut ready for finishing Finished...Farecla Black Foam Finishing Pad and Lime Prime used... The advantages of this system is a true finish to match the surrounding paint finish, wet sanding however creates a slightly more flatter surface than the paint around it, another advantage is the time and effort it takes to polish the repaired area, and the main advantage is one where thin paint does not allow the wet sanding technique to be performed as strikethrough may occur due to the flatting and the polish needed to bring out the finish, this affecting quality of the repair itself, obviously this would have been assessed before hand. The main disadvantages are that if a mistake with the block is made and you snag the edge it will lead to another repair if it cuts through the clearcoat, I have only seen this once and it was done as a demo, too much pressure allowed the block to grip and shave straight through the clearcoat, I would say that another disadvantage is time, but the time taken for the paint to dry is the same as it is in wet sanding methods, therefore the cutting technique could well be a little quicker due to less finishing, although this is slight. A lot may seem this as a bit of a gimmick method, but if it is not tried and tested how would anyone know how good the results are. I have spent full days repairing scratches to whole vehicles using this method, if you can imagine scratches on every panel, sometimes as long as the panel and some as small as a centimetre long, imagine wet sanding all the scratch repairs, a long time polishing is ahead, you may think if the damage is such then why not repaint it, cost, materials and time spring to mind, in a refurbishment centre time and money was of the essence and if I could do this sort of thing in a day or so instead of a week, then it works for me. Well that’s the info on the cutting technique for scratch repair, hope you find it useful…. Stone chip Repair.... This system can also be used on slight surface scratches....this however is almost the same as one posted in another thread in the showroom....difference being I dont use lighter fluid or enamel paints.... To achieve results of almost 95-99% it is imperative to have the correct colour mixed by your local bodyshop consumables supplier or internet sites that do paint mixing.... Once the colour has been sourced....in this instance BMW Jerez Black its time to crack on....the colour itself is mixed with Cellulose clearcoat as this will form the shine on the surface of the chip filled....the process is below.... Stone chips on the front bumper.... img src="http://i415.photobucket.com/albums/pp234/b0dyr0ck2006/washing%20technique/ebe73c8d.jpg" alt="" /> The process was to cover the bumper in paint, solvent base with cellulose clear mixed in....it is applied with a lint free cloth and left to dry....the heavier stone chips were touched in and cut as well.... Doesn't look a pretty sight but it is effective, as you will find out, it was polished back with Farecla Total and a Scholl Orange Pad, which was on its way out so making a mess of it wasnt a problem.... This one was finished with Zaino all in one and a quick shufty of Z3 and Z8....the results and smile on the owners face are worth the effort alone....although he doesnt look very smiley faced the pic.... Hope these guides have helped and entice you all into giving it a go.... Written by Reflectology on Detailing World
Looks like a lot of hassle. With the way our buses skim the earth evading stones "not" I'd be out there for hours every weekend For me a DOB of paint is as good as it gets.
