how do you finish polish

[bmuss51]

I'm working on my first engine which has brass and bronze parts.and in the past i have seen models at shows which are highly polished. but i have tried on the big surfaces which is flat or close to flat i have no problem. but on small areas and things that have recesses i have problems finding ways to get in the small area. like even some files i can't even seem to get in those areas to get rid of the casting surface let alone to get in those areas to polish.heck, i have tried using dremel type of tools but to get in some of the small areas it seems they are even to big. so can you give some input of how you finish your model!
and after they are polished what ways do you keep them from going dull. like i have seen to put clear lacquer on the parts . but how do you keep from getting runs or a build up . or would a good waxing last and be as good looking on a model. but keep in mind that this model i plan to run and not just sit there to look pretty. and personally i like the semi polish or satin look better than the high polish .

 

[Mainer]

I mostly don't polish much, so I'm probably no one to be making comments, but I will anyway. ;D

I think for best appearance, one should strive to maintain crisp, sharp edges and corners. I've seen highly-polished models that look sort of melted, because all the crispness has been polished off.

I also favor a satin finish, generally, rather than a high-gloss polish. I suppose one might be able to make a case that a "scale" surface finish should be high gloss, but to me it doesn't look right.

When I have dealt with surface finish, I've generally used about 220 paper to get the level of finish I want. For flat surfaces, when I can I lay the paper on my surface plate and stroke the parts across it, to maintain flatness and sharp edges. I've used Cratex abrasive points to get into corners and things.

To preserve a polished finish, a dip in lacquer, thinned about 50%, might do it.

 

[Mutley]

I have had good results on small items with these:- http://cgi.ebay.co.uk/6PCE-RUBBER-P...700|66:2|65:12|39:1|240:1318#ebayphotohosting

They work well if you keep them lubricated with metal polish, this helps keep the heat down.

 

[Mainer]

You speak of "getting rid of the casting surface." An alternative to polishing it away would be to fill it, which would be the way it would probably be done in full-size practice. Autobody filler or something like that.

 

[b.lindsey]

Well it seems to me that one of the advantages of building from castings it the "casting" look which seems more realistic to many (me included) as opposed to bar stock projects. I totally agree with Mainer on that score and find the sharp edges and corners and a satin or brushed finish most appealing. It does take time and care and a good flat surface and LOTS of elbow grease. Only thing i can add is that for round pieces I chuck them in the lathe and let the lathe do most of the work. Fine 320 grit paper can stil be used but I have found ScotchBrite to work very well also on round stock and impart a nice satin or brushed finish with little to no stock removal.

 

[bmuss51]

thanks for the comments so far. and i agree that a satin finish is what i perfer. but trying to get those results with the dremel points that was brought up . i have had some mixed results with the finish. like they smooth the surface in the tight corners. but when you get to bigger areas it's hard to get an even finish without having swirl marks.
as for the lacquer finishing sys, i was not aware to thin it to 50%,so thank you.

 

[rleete]

Before dipping/spraying the part, warm it up a bit. Hair dryer or even just wrapping it in a clean rag and holding it under your arm for a while. This helps the laquer to flow better, and have a better surface finish.

Remember, warm, not hot. If it's too hot to hold in a bare hand, let it cool a little.

 

[bmuss51]

as for the lacquer finish which I'm starting to like the suggestions. but what is a good source, like last night i looked at a local hardware store and came up empty except for spray cans. and right now I'm thinking auto lacquer will be very expensive.

 

[Dhow Nunda wallah]

Try your friendly neighbourhood dentist

The rubber-abrasive tools they use for polishing teeth are great. You also get all kinds of carbides and diamonds.
They are pretty much use once and toss em, in the dental trade.

It may help if you offer a few bucks to cover costs (they will autoclave em before giving em to you) or maybe a little offer of help from your workshop, as a contra deal.

I'm in a fortunate position. Mate's daughter is a dental nurse and keeps me well supplied.
Be aware that dental tools come in 2 types: RA (right angle, low speed); and HS (high speed, der)
edit to say, that dental tools, anything under 50,000 RPM is low speed.
Both these types will chuck in a standard Dremel type collet.

Hope this helps
Regards,
Lin

 

[bquiggle]

Just a suggestion from the silver smithing world, use a hard felt mandrel mounted on an electric motor with tripoli polish to remove all scratches, wash and dry it, then finish polish it with rouge on a soft muslin wheel, you should be able to get a mirror finish if that's what you want.
Or use a brass brushed wheel to get a satin finish.
A small parts clamp is essential in holding parts while you do this unless you like ducking flying parts when they are ripped from your hand
Tripoli and rouge and the wheels can be found at any jewelry supply company

 

[bearcar1]

Crocus cloth when used after fine grit sanding can bring the surface up to a nice luster as well. Then the application of a paste polish such as Semi-Chrome etc. provides appealing finishes fairly easily. As for the spraying or the brushing of clearcoats, I have to admit that I have not hd good fortune with them. I was doing something wrong as the coatings would turn out either too thick or thin etc.

 

[bmuss51]

OK,i finally got the polishing done with the help i saw here and alot of dremel and elbow grease. but i saw in one of the posts about thinning clear lacquer.and now i have some ?'s on that, like what type of lacquer is used? because the only thing i could find at the local hardware store is a wood gloss clear lacquer for brushing which says on the container not for spraying and do not thin. where in the post it said to thin 50%. and i did check out the local auto supply for a clear gloss and the price is out of this world, like $68 for a quart and another $24 for an activator. and that is for a poly type of paint,because they told me they can't even get lacquer any more.
so, could i please get somemore input?

also did any of you try a semi gloss? is there a big diff. in the final appearance if you are looking for a semi or satin type of appearance on the brass.

i am not looking for a mirror type of finish, but one of a satin type.

 

[shred]

I have just acquired a can of this: http://www.brownells.com/aspx/ns/store/ProductDetail.aspx?p=1164&title=METAL-COAT EPOXY on suggestion of another model maker.

I've not tried it yet, but most Brownells stuff is pretty good.

 

[RICHARDDV]

I USE A SPRAY LACQUER TO PROTECT MY BRASS PARTS IN MY TOYS SETS WITH EXCELLENT RESULTS . I BUY IT AT THE LOCAL HARDWARE STORE UNDER THE TRADE MAME OF "DEFT" . IT IS AVAILABLE IN SATIN , SEMI-GLOSS ,AND GLOSS AND IS HANDY TO USE IN AN AEROSOL CONTAINER AS WELL AS QUARTS AND GALLONS. BE CAREFUL BECAUSE IT IS ALSO AVAILABLE IN THE BRUSHABLE ,NO THIN ALSO. SO READ THE LABELS---- RICHARD

 

[bmuss51]

deft is the product i bought , and i did notice that it said brushing. so i asked at the paint dept what is the diff from spray and brushing. and they came back and told me it is how thin the paint is. so i bought it and when i got home i decided to read the rest of the can. and that's when i noticed, do not thin or spray.and i remember looking at the other cans there before i bought and all said brushing.
so i guess that can will be returned and i will have to look else where to find something useful.but there's some places i have not looked yet like Lowe's or homedepot.
as for the epoxy type of spray, I'm alittle reluctant to try because of the dry time and if you don't get a good finish on it the first time, you probably are up the creek.and the other reason is, in a spray it is possible to get uneven coverage in tight areas and then to cover it good there will be runs.

 

[Mainer]

I don't understand the caution against thinning. I think I would thin it anyway and see what happened.

 

[RICHARDDV]

ON THE QUESTION OF SPRAYING BRUSHABLE LACQUER , I HAVE HAD THE OPPORTUNITY TO SPRAY SOME DEFT BRUSHABLE LACQUER AT WORK THIS WEEK. OUR PROCUREMENT DEPARTMENT EVIDENTLY CANT READ SPECS AND GOT THE WRONG KIND OF DEFT FOR A RUSH JOB ON SOME BRASS CASHIER CAGE BARS AND I WAS FORCED TO SPRAY TO COMPLETE ON TIME. I HAD NO PROBLEM WITH A 5% THINNING EXCEPT FOR THE ACCELERATED DRY TIME. IT WAS DRY TO THE TOUCH IN 2 -3 MIN. SO EXTRA COATS WERE ABLE TO BE MADE ALMOST IMMEDIATELY. USE LIGHT COATS UNTIL BASE HAS BEEN ESTABLISHED THEN LAY ON FINISH TOP COAT. GOOD LUCK RICHARD

 

[bmuss51]

richardd:
what you have said in your post suprises me. and by that i mean you only thinned 5% because i thought 50% was a normal thinning for spraying. but most of the parts i want to do i would like to dip. or would spraying be better. and as for the parts they will be things like the carb, pipes, and ignitor parts which have small areas and alot of contour. which i have always had lots of problems keeping from getting runs by spraying and still get into the concave sections of things.that's why i was thinking of dip and sling method. but i can see a problem on lets say the carb by getting lacquer in areas where fuel will be and then start to gum up and clog up the workings. and even in the intake which is a brass tube there would be lacquer on the inside of the tube only to get fuel passing through it causing it to get soft and even dissolve.
i have not mentioned it yet but what i'm finishing up is a half scale of a new holland hit-n-miss which i plan down the road to hook up to an ice cream freezer.

 

[RICHARDDV]

Brushable lacquer is self leveling so it did not need to be thinned to much , mostly to assist in the drying time. To much thinner made it to hot ( fast drying ). 5% seems to make it flow better thru the nozzel and gave an even coat and reduced the tendacy to run. If you are going to dip coat then a thinner consistacy would be more preferabut watch for edge accumulations at the bottom of the part. Richard