before or after for paint job????

i have a cylinder block i need to bore and paint
i was wondering if i should sand blast and paint before i send it to APE racing for boring ,or do it after wards?
if i do it after bore job, i may mess it up right!
all advise will help out!
oh yeah, i know sand blasting is not the best as bead blasting, but the custom harley builder i work with says he does it all the time for ALL his harley aluminum and steel parts on his bikes and others as well, and never had any problems, and it looks so good and clean.
i will also use a parts washer afterwards and then industrial degreaser at my shop and then paint it with high temp black paint
oh yeah, he also loves these old kzs to, and said he owned one (kz550) 20+years ago!

Send the parts out first. The various machining operations will require repetitive clamping to be done to the pieces, which would mess up any applied finish.

Get the parts back, stuff the bores with clean rags, mask the mating surfaces, then cover the mask with duct tape and trim with a razor blade. Make a cardboard/plastic sheet template to cover the head gasket mask, and duct tape that down. The tighter and tougher you make the mask, the less risks you take.

Your boss is likey to be using a larger-grain form of sand, and it may suit his applications, given cylinder-blacking is the usual par for his course, but even larger-grain silicas will shatter on impact with the metal, leaving a microscopic dust residue. *NO* form of silica quartz blasting will ever match the finish of glass beading on aluminum. Period.

Depending on the vintage of the motors he's working on, he's also blasting iron heads/jugs, which is a different animal entirely.

Fot the purporse of painting freshly-beaded/blasted aluminum, I'd stay away from chemical parts washers like Safety Kleen and the like.

The best process is to pull the freshly blasted part from the blaster, pull the masking, blow it off thouroughly with a moisture-filtered air source, re-mask, blow again, and start slinging your high-temp paint immediately. Exposing raw aluminum metal to air begins the oxidation process. You've realistically got a couple of hours to putz around, but I'd get after it ASAP.

If you've got to wash the parts prior to painting, do it with a fast reducer - dries quick and leaves practically no residues.

yes your right he does have iron jugs on his bike (1960 harley all original w/ 1300 miles on it)
the chemical washer in my shop is used for cleaning zinc parts and bronze and copper and steel! all for electric motor parts
im not to sure what they use as a cleaner, but i know its nothing you will find on any shelf at auto parts store.(industrial chemicals )
so i should NOT use a chem.. bath to clean and degrease it before i paint it? i was told blasting wont get all oil/grease off and paint may not hold right.
ill just give it a good air blowing and make sure its nice and clean then paint it a.s.a.p when done blasting it.

heres a pic of his bike w/jocky shit

resized pic

steveo_4192003 wrote:

...so i should NOT use a chem.. bath to clean and degrease it before i paint it? i was told blasting wont get all oil/grease off and paint may not hold right.

Any well done bead blasting job worthy of the name will.

An off-the-shelf otion for de-greasing aluminum is good 'ole brake cleaner. $3 a can. Works wonders.

If it's a concern, spray the bejeesus out of your parts with the brake cleaner, wire brush the gunk off and re-spray to rinse. Repeat as necessary/desired. Let dry and blast.

ill just give it a good air blowing and make sure its nice and clean then paint it a.s.a.p when done blasting it.

Yep. That'll do it.

I've had aluminum parts beadblasted clean if necessary before going to the machine shop. Cast iron parts I've had hot tanked at the machine shop, but everything goes in the laundry tub with warm water and detergent when it comes back (not cranks etc!) to finish degreasing, clean out passages and clean freshly bored cylinders. Use rags, scrub brushes, pipe cleaners etc to clean the parts. Give the parts a good rinse in hot water, allow it drain for a few minute, blow out passages etc with compressed air if possible and don't let your wife see you placing parts over heater/ac vents to dry them. Bores are wiped dry/clean with a white rag and are only clean when the rag comes out dry and still white.
Mask off areas you don't want painted and use a good quality spray can engine paint. I've had good luck with Duplicolors engine enamels.

I agree with Pterosaur. I wouldn't paint until it comes back from the shop. If your finish gets messed up it won't be fun to do the same job twice.

hoping NOT to be offensive here.
i have been a painter for some 35 yrs. off and on.
NO RAGS and use on paint related materials for painting. ONLY !
I have seen more than just a couple of times motors blown up and the cause was the guy wiped and cleaned the internals with those shop rags. You know the orange and blue ones. They left so much lint that it all gathered in the oil pump screen and restricted oil flow to the point of starvation. I assume you are talking about EXTRNAL PARTS? Samething. Ever paint something and see all the little hair looking things in it? LINT! From the rag you just wiped it off with.
Use the proper paint related materials and AIR!
Try your best not to even touch anything with your bare fingers. your body leaves oil. And remember if you are painting ALUMINUM, there is a aluminum primer, that is obvioulsy different than regular primers.
SAND BLAST?..OH NO !!!!
Sand actually removes soft metal. Think not? Hold a sand blast nozzle on some aluminum for a few seconds and you can see that the actual metal is being pushed in the direction of the blast. VERY easy to distort aluminum with sand balsting.
GLASS BEAD....is exactly as it sounds. Little round beads of glass. They break up as they hit and do not cause any deformation.
The Harey friend you have? Well I have onwed Harleys for 30 yrs. so I mean no offense. BUT....save the sand blasting for items like steel and iron.
Anyone hear of SODA BLASTING?
Getting a hood and door done in a few eeks useing this method. I will let everyone know how it works out when done. They actually blast baking soda. Of course different size particles for different jobs.
Just my pathetic thoughts

Recalling the dental cleaning pressure spray uses soda to sparkle your pearlies.

ive used the baking soda for having car bodys stripped before it works good just make sure you clean it all out really good,ive brought up the shop rag issue before and it does leave lint in cylinder bores ive always just used carb cleaner and wadded up toilet paper just keep spraying and rubbing till you dont get anymore black crud coming out on toilet paper from bores;)

edspring1 wrote:

hoping NOT to be offensive here.
i have been a painter for some 35 yrs. off and on.
NO RAGS and use on paint related materials for painting. ONLY !
I have seen more than just a couple of times motors blown up and the cause was the guy wiped and cleaned the internals with those shop rags. You know the orange and blue ones. They left so much lint that it all gathered in the oil pump screen and restricted oil flow to the point of starvation. I assume you are talking about EXTRNAL PARTS? Samething. Ever paint something and see all the little hair looking things in it? LINT! From the rag you just wiped it off with.
Use the proper paint related materials and AIR!
Try your best not to even touch anything with your bare fingers. your body leaves oil. And remember if you are painting ALUMINUM, there is a aluminum primer, that is obvioulsy different than regular primers.
SAND BLAST?..OH NO !!!!
Sand actually removes soft metal. Think not? Hold a sand blast nozzle on some aluminum for a few seconds and you can see that the actual metal is being pushed in the direction of the blast. VERY easy to distort aluminum with sand balsting.
GLASS BEAD....is exactly as it sounds. Little round beads of glass. They break up as they hit and do not cause any deformation.
The Harey friend you have? Well I have onwed Harleys for 30 yrs. so I mean no offense. BUT....save the sand blasting for items like steel and iron.
Anyone hear of SODA BLASTING?
Getting a hood and door done in a few eeks useing this method. I will let everyone know how it works out when done. They actually blast baking soda. Of course different size particles for different jobs.
Just my pathetic thoughts

I have to agree with you, don't use shop rags or any other rags that will leave lint. I use old washed t shirts without ripping them or cutting them up. I've done quite a few engines this way and never had a problem. It should go without saying, but all passages must be checked no matter how you clean your parts.

ok, i talked to boss man at work! indeed, he used glass beads as form of blasting media for his alum...
we argued for a min... the first time he said sand blast ,not bead blast...
he also said i should degrease (break cleaner)it before blasting.
thanks all, i now know what i need to prep this for painting!!! just need time and money!!!!!!:pinch: