Scratch Shrinkage Problem

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Placing items in the sun ? Wouldnt that cure from the outside in of the 2nd coat the drys faster then the 1st leaving the underlayer the 1st coat full of solvent that would trapped ?
 
strum456;30832 said:
Not exactly. This was stripped to bare metal. I sprayed 2 coats of epoxy an hour apart. I kept the piece inside overnight and skimmed the whole panel with filler the next day (it sat for at least 24 hours).

I cut my filler with 80. I used some dolphin glaze here and there and blocked everything with 180. I believe I did a quick pass with 320 too.

I sprayed 1 coat of epoxy and set the panel in the sun for an hour. I took the panel in, allowed it to cool and shot my second coat. Then I put it back out in the sun for the remainder of the day and then next morning. I positioned the part to get sun all morning, and I blocked it around noon with 80, then 180 and 320. After another hour or so in the sun, I cooled the panel and sprayed another coat. I sunned it for an hour and then shot the second. Same process - the next day around noon, I blocked it with 180 - 320, sunned it for an hour, sprayed 1st coat, sun for an hour, and sprayed coat 2.

I repeated the above process until the panel was straight. I used black epoxy for build and gray epoxy as guide coat. After everything was straight, I laid the panel outside for a week before a final blocking with 320, then 400 and 600 wet.

I used prospray black base. I sprayed one coat in the morning. Went to our farm during the day, and sprayed coats 2 and 3 an hour apart that evening. The next day I sprayed 4 coats of clear, 30 minutes apart. One day later I put the part in the sun all day. the next day I sanded it with 400, and sat it out 2 days.The 3rd day I sanded it with 600 and then flow coated with 2 coats, 30 minutes apart.

FEEL FREE TO SHOOT HOLES IN MY PROCESS GUYS. I WANT TO LEARN!
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From my count thats 13 coats of material not counting how many times u repeated the process with sunning between and sanding reapply more material thats alot of material
 
lethalcx;31281 said:
Sorry 18 coats
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I didn't count his coats because I never count mine, So I will take you at your word and assume there was 18 coats of material applied, that is a lot of material, However, most of it ended up in the floor after it was block sanded, so the initial amount of material was likely cut to 1/4 if not less in the primer area, then the 4 coats of clear was likely cut and buffed which probably left about 1/2 of that. So, in the end he likely has about 2-3 coats of primer, 3 coats of base and 2-3 coats of clear actually left on the car. Just trying to put things into perspective if you are not familiar with the painting process.

Kelly
 
i have used the epoxy on these plastic parts i do frequently that have a deep leathery texture to them. it takes a good 6 coats or so of the epoxy to do it but it will tell you it takes a real long time for the epoxy to harden up with high build like that. these particular parts i always let sit for atleast a couple weeks before i sand and base them out. once its all done though they look fantastic and i have seen them that i did 1 and 2 years later and they still look good with no shrinkage. when i used to use adpro and 2k i would get shrinkage with them within the first week. the epoxy has waaay less shrink to it as a building primer but its really gotta be done right. solvents remaining in the film will slow the epoxy cure down to almost a stand still. i believe the sun is a problem. your skinning it over and trapping a little solvent in the epoxy layers underneath and probably the oem paint as well. like shine, i always let the epoxy sit a day or two before applying a little heat.
 
I was kind of wondering about the directly into the sun thing, that is something I have never done. It's known that too fast of reducer and/or too fast of infrared lamp application can result in solvents being trapped below a partially cured skin. It's not too big a leap to assume the the sun could produce the same effect, although Barry has always been big on the sun as kind of a cure-all for solvent trapping related problems. So there is a bit of a rub here as to the established cause of this problem.
 
The surface temperatures are wild this time of year, so I also believe the sun was the problem with not only the uncontrolled temps but also the uv rays which need to be factored in...I think the op should just wait a day before putting outside and his procedures would be good
 
exactly . and i also do not leave it out all day. here in texas if you leave one in the sun all day you can strip it like using a heat gun . i leave it out about an hour .

also if you do not fully understand the process of using epoxy only then you should not be using it. you would be better off using some other primer .
 
I agree with everyone about the sun now tell me this on the 99 integra strum put a coat of turbo after all the coats of epoxy on , now would that also trap the solvent and not let the epoxy escape and cause problems also ? Turbo does dry fast and wouldn't it be better to use turbo instead of epoxy
 
i doubt it. it was just one coat if i read right. urethane primers tend to breath and not seal in solvents anywhere near like an epoxy would. epoxy being completely waterproof and very resin rich. dontt get me wrong it prob doesnt help matters but i dont think it was the major contributor.
 
I thought I was doing the best possible job by using all epoxy and sun baking between coats. It sounds like my process needs to change. If I'm following you guys here....epoxy is so air tight once it is cured that its own solvents can't even pass through it. By sunning the epoxy, the top "skin" is reaching full cure too fast and thus trapping underlying solvents. I would have never guessed that this would be a problem when applying only one or two coats per session. I am really starting to consider trying Slick Sand or some other poly primer. I understand it does not sand quite as well as SPI epoxy, but maybe it will be worth it if I can cut down on the amount of epoxy I'm using. I always try to take my time to produce the best possible results. But, it is sounding like doing the all epoxy method the right way may take even more time than had ever thought.
 
i induce my epoxy overnight , use a 2.3 and shoot only one heavy double coat at a time. 24 hrs cure then block . an hour or so in the sun the repeat as needed. i have never had any shrinkage in epoxy. i have had shrinkage and swelling with polyesters .
 
shine;31300 said:
i induce my epoxy overnight , use a 2.3 and shoot only one heavy double coat at a time. 24 hrs cure then block . an hour or so in the sun the repeat as needed. i have never had any shrinkage in epoxy. i have had shrinkage and swelling with polyesters .
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If I remember correctly, you spray epoxy over 100 grit scratches? So, you can double coat and spray over pretty coarse scratches with no ill effects because epoxy is such a stable coating. It seems that I am learning the hard way that epoxy is extremely stable EXCEPT when you put it in the sun too soon and trap solvents.

Barry, what do you think about all of this?
 
strum, you gotta remember that paint shrinks from only one thing.....solvents leaving the film. the trick is just determining where, when and how. maybe it is the sun and maybe its not. maybe its the oem paint soaking it up or a little of both. sitting in the sun and or heating the epoxy to cure is no problem but possibly doing it too soon may be an issue. if the oem paint soaked up some of the solvent then the epoxy skinned over sealing them in then that would be an issue. i do think you would see a difference in the future if you didnt sit in the sun for each coat. just get the epoxy all on with normal flash, let it sit for a day then move out in the sun. it would just allow the epoxy to stay open longer and the solvents to escape. all we can do here though is just guess since none of us were there and your procedure is pretty good. those plastic parts i use the epoxy on i will do all six coats in one shot, 20 min flash between. they are just air dried for 2 weeks then finally before i sand them i will bake under a lamp for a few hours.
 
Do you really think solvent is still escaping from oem baked on paint from 1999 ? I worked at a few dealerships them cars are brand new and waxed before there sold and their is no oem manufacturer saying no wax for 6 months new cars are powercoated in a way electrostatic and baked on , solvent wouldnt be an issue off the oem finish , Wouldnt the best process for the job be 2k let it dry good block and paint what is the need for several coats of epoxy ? Epoxy 1 coat 1st then 2k all I can see happening is too many layers build by epoxy that stays open for a long period of time once filler is applied and covered with more epoxy more body work and more materials once its covered with base coat clear and in this case sanded and more clear applied its just layers of material and any solvent trapped by over 20 layers , I just for see issues of solvent trying to escape and if it cant breathe out it can go down all the way to the 1st layer of epoxy and filler coats causing bubbles from solvent that can't escape , I did see a post where berry said cut the bubble open and smell for solvent
 
No its not but dont forget your letting wet solvents sit on top of that old oem paint for an extended period. The solvents from the primer will certainly penetrate down into the oem paint.
 
lethalcx;31306 said:
Do you really think solvent is still escaping from oem baked on paint from 1999 ? I worked at a few dealerships them cars are brand new and waxed before there sold and their is no oem manufacturer saying no wax for 6 months new cars are powercoated in a way electrostatic and baked on , solvent wouldnt be an issue off the oem finish , Wouldnt the best process for the job be 2k let it dry good block and paint what is the need for several coats of epoxy ? Epoxy 1 coat 1st then 2k all I can see happening is too many layers build by epoxy that stays open for a long period of time once filler is applied and covered with more epoxy more body work and more materials once its covered with base coat clear and in this case sanded and more clear applied its just layers of material and any solvent trapped by over 20 layers , I just for see issues of solvent trying to escape and if it cant breathe out it can go down all the way to the 1st layer of epoxy and filler coats causing bubbles from solvent that can't escape , I did see a post where berry said cut the bubble open and smell for solvent
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I think that maybe your frustration is making you over think the situation....your procedure was ok .....just put the piece in the sun too soon....easily fixed next time and you will be happy with the results...we have all been there on the "I thought I did everything I could" syndrome...you did...timing was the mistake in my humble opinion...you are obviously a craftsman
 
as i said , if you do not understand the use of epoxy stay away from it . trying to blame the epoxy and suggest 2k would be better tells me you do not understand epoxy or it's use. any product placed immediately in the sun will do the same thing .
 
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